Triple Science Physics

P1, P2 and P3

Core Questions and Keywords and Definitions

P1 Core Questions

P1 Topic 2 Core Questions Which scientist discovered infra-red radiation? William Herschel

Which scientist discovered ultra-violet radiation? Johann Ritter

What are the colours of light in the visible spectrum? (Start with the longest wavelength)

Red, Orange, Yellow, Green, Blue, Indigo, Violet.

What is the order of waves in the electromagnetic spectrum? (Start with the longest wavelength)

Radio waves, Microwaves, Infrared waves, Visible light, Ultraviolet rays, X-rays, Gamma rays.

Are the electromagnetic waves transverse or longitudinal Transverse

Which travels faster in a vacuum light or radio waves? Neither, all electromagnetic waves travel at the same speed in a vacuum.

Which end of the electromagnetic spectrum has waves of the longest wavelength?

Radio waves

Which end of the electromagnetic spectrum has waves of the highest frequency?

Gamma rays

Describe how to measure the focal length of the lens. First you measure the distance / length (1) from the lens to image / screen / focal point (1)

Explain what the eyepiece lens does. An eyepiece lens magnifies the image (1). An eyepiece lens also

refracts the light (1)

Describe the image the student sees when he looks through the lens.

When looking through an eyepiece lens you would see

a magnified (1), erect (1) and virtual (1) image of the object

A ray of light changes direction when it enters a converging lens, what is this called?

Refraction

How does the eyepiece on a simple telescope work?

The eyepiece lens is a small converging lens that is used to magnify the image produced by the larger converging lens at the other end of the telescope.

What do waves transfer? Energy and information but not matter

What is the difference between a real and a virtual image? A real image is when the rays of light are bought together by a lens and the image is observed on a screen, whereas a virtual image is when the image is observed on a surface like a mirror.

What changes when light enters a denser material? The speed and direction of the light ray

What is the difference between the geocentric and the heliocentric models of the universe?

The geocentric model has the earth at the centre of the solar system and everything else orbiting around it. Whereas the heliocentric has the sun at the centre and the planets orbiting around it.

Explain how Galileo's observations supported the heliocentric model of the solar system

Galileo observed 4 moons (1) orbiting Jupiter (1) and not Earth, therefore not everything orbits the Earth (1)

What do light waves transfer? Energy and information

State an example of a longitudinal wave. P-wave, ultrasound, infrasound, sound, P waves (each worth 1)

Give examples of transverse waves All of the electromagnetic waves including light etc. and seismic S (secondary) waves.

Describe what happens to particles in longitudinal waves The direction of the vibration is the same as the direction of energy travel

Describe what happens to particles in transverse waves The direction of the vibration is perpendicular/at a right angle to the direction of energy travel

Describe the motion of particles in a material when this ultrasound wave passes through.

When a P waves occur, the particles vibrate/oscillate (1) in the

same direction as/parallel to the direction of the wave travels

(1)

What is the frequency of a wave and what is it measured in? The number of waves in 1 second and the unit is Hertz (Hz)

What is the wavelength and what is it measured in? The length of 1 complete wave cycle. It is measured in meters

(m).

What is the amplitude and what is it measured in?

The distance from the centre of a wave to the top of the wave. It is measured in meters (m).

As the frequency of a wave increases, what happens to the potential danger?

It increases too because of the increased energy.

What are the harmful effects of excessive exposure to: 1. Microwaves 2. Infrared 3. Ultraviolet 4. X-rays and gamma rays?

1. Internal heating of body cells 2. Skin burns 3. Damage to surface cells and eyes, leading to skin

cancer and eye conditions 4. Mutation or damage to cells in the body

Name some of the uses of: 1. Radio waves 2. Microwaves 3. Infrared 4. Visible light 5. Ultraviolet 6. X-rays 7. Gamma rays

1. Broadcasting, communications and satellite transmissions.

2. Cooking, communications and satellite transmissions 3. Cooking, thermal imaging, short range

communications, optical fibres, TV remote controls and security systems.

4. Vision, photography and illumination. 5. Security marking, fluorescent lamps, detecting forged

bank notes, disinfecting water. 6. Observing the internal structure of objects, airport

security scanners and medical X-rays. 7. Sterilising food and medical equipment and the

detection of cancer and its treatment. 8.

Describe a harmful effect of ultraviolet waves. Dangers of UV radiation include damage to skin, sunburn, skin cancer, damage to eyes, eye problems, cataracts (Each worth 1 mark)

Which type of radiation in the electromagnetic spectrum is likely to be the most dangerous?

This would be gamma rays/γ (1)

Suggest other ways in which people can protect themselves from these ultraviolet waves.

They can wear sunscreen/suncream, sunglasses/UV glasses,

go into shade/stay indoors, wear protective clothing (Each

worth 1 mark)

Describe one use of ultraviolet radiation. A use of UV radiation can be:

security marking (1) where ink absorbs UV and re-radiates (visible) light (1)

fluorescent lamps (1) where coating absorbs UV and reradiates (visible) light (1)

genuine bank notes (1) in which the watermark absorbs UV and reradiates (visible) light (1)

disinfecting water (1) where the UV kills bacteria (1)

sun beds (1) where UV absorbed by (melanin in) skin (1)

Which part of the electromagnetic spectrum has the highest frequency?

Gamma rays (1) have the highest frequency

X-rays have many uses.

Describe one use for X-rays other than medical uses.

A use of X-ray radiation can be:

(at the) airport /customs / docks / security checks (1) for

dangerous/illegal items (1)

checking welds (1) to examine under the surface (1)

checking paintings eq (1) to look for detail under the top

paint layer (1)

X-ray telescopes/astronomy (1) to study/look at objects in

space (1)

check packaging e.g. cans/packets (1) (to see if) filled to

correct level (1)

sterilising (1) food/hospital equipment (1)

How many different colours are there in visible light? 7

What is the name of the ionising radiations is from a radioactive source and is also part of the electromagnetic spectrum?

Gamma rays

Infrared is used in an electric toaster. Infrared is also used by

television remote control.

Explain why using a television remote control does not burn anyone.

The wavelength/frequency of the infra-red radiation in the

toaster is of a higher frequency (1)

In the electromagnetic spectrum, what radiation is between radio waves and infra-red radiation?

Microwaves

Some users believed that sunglasses would protect their eyes

from the X-rays.

Explain how effective this would be as a precaution.

The result would not be not effective (1) because X-rays can

easily penetrate sunglasses (1)

Name the radiation that causes skin cancer UV radiation

Describe a use of gamma radiation. Any of the following:

Sterilising food /medical equipment

Detection / treatment of cancer imaging /detect flaws in materials

Microwaves can be used for satellite communications.

State another use for microwaves.

Any of the following:

Cooking

Monitoring the weather / mobile phones

Name 3 types of ionising radiation that transfer energy? Alpha particles, beta particles and gamma rays

Where does ionising radiation come from? Radioactive sources continuously emit ionising radiation.

P1 Topic 3 Core Questions What is the solar system and what is it part of? It is made up of the sun and the 8 planets that orbit it and it is

part of the milky way galaxy.

Put the following in order of size starting with the smallest. Sun, universe, moon, planet, galaxy, earth.

Moon, Planets (Earth), Sun, Galaxy, Universe.

What is the definition of a galaxy? A cluster of stars

Our Solar System is near the edge of a galaxy called the . . . Milky way

Large telescopes which collect visible light to explore the

Universe are usually placed near the tops of mountains.

Suggest why radio telescopes do not have to be placed high

up a mountain.

Because radio waves are not absorbed by the atmosphere (1)

Suggest why, when a galaxy has a very large red-shift, some of its visible light is not detected through the Earth’s atmosphere.

Because light might be shifted into infrared region (1) and

some infrared is absorbed by atmosphere (1)

Name one type of radiation that can reach the surface of the Earth from stars.

Any one of

Radio waves

visible light waves

microwaves

Name one type of radiation from stars that cannot be detected at the Earth's surface but can be detected using satellites.

Any one of

X-ray

gamma ray

far infrared

Name one type of electromagnetic radiation that satellites on

the Earth’s surface can detect.

Both radio (waves) (1) and microwaves (1) can be detected on

the Earth’s surface.

Suggest why radio telescopes do not have to be placed high up a mountain.

Radio waves are not absorbed by the atmosphere

Some scientists look for signs of water on other planets.

Suggest why they do this.

As water is needed for life, if water is found then it gives

possibility of life

What methods are used to search for life beyond earth? Space probes orbit other planets like mars photographing the surface so Scientists can decide where water might have been. The scientists can then land Landers to do soil experiments and look for life in the most promising spots. SETI analyses radio waves from space for signals from extra-terrestrial life.

What is a spectrometer? A device that can split up the different wavelengths of light. (It splits light into its different colours).

State what a nebula is (cloud of) dust and/or gases (1)

A nebula is a cloud of gas and dust where stars are formed.

A hot object forms when gas and dust in a nebula come

together. Explain why the gas and dust come together and

form a hot object.

The gas and dust is pulled together by gravity (1) which then

converts gravitational/kinetic energy into thermal energy(1)

Describe how the mass of a main sequence star will affect

what the star finally becomes.

Stars with a similar or smaller mass of our sun will become a

white/black dwarf (1)

Whereas a more massive will become a neutron star / black

hole (1)

Describe the life cycle of stars like our Sun Stage 1: Nebula - a cloud of dust and gases (mainly hydrogen) pulled together by gravity. Stage 2: Star (main sequence) - As the nebula grows the gravitational pull gets stronger and the pressure and the heat builds resulting in the formation of a star. Stage 3: Red giant - When most of the hydrogen has fused into helium the core collapses and the outer layers expand. Stage 4: White dwarf - The red dwarf throws off a shell of gas and what remains will be pulled together by gravity and collapses. No further reactions happen inside a white dwarf.

What is the Big Bang theory? The whole universe started out as a tiny point of concentrated energy about 13.5 billion years ago. Since the big bang the universe has been expanding ever since.

What is the Steady State theory? The universe has always existed and has been continuously expanding with new matter being created as it expands.

The Steady State Theory is not as widely accepted as the Big

Bang Theory. Suggest a reason for this.

Because there is more evidence for the big bang theory (1), it

is also more reliable as cosmic background radiation does not

support Steady State theory (1)

How do we know that galaxies further way from us are moving faster than galaxies closer to us?

The faster a galaxy moves, the more red shift is seen. Observations show us that there is more red shift from more distant galaxies and so they must be moving faster.

CMB is an abbreviation for. . . Cosmic microwave background radiation

P1 Topic 4 Core Questions

The frequency of ultrasound is more than 20 000 Hz

Ultrasound is used for Communication between animals, Sonar and foetal scanning

Explain why ultrasound rather than X-rays are used for foetal scanning.

Ultrasound is not dangerous (1) but X-rays are because they can damage to tissue/DNA OR mutate cells (1) in the body.

Describe what is meant by infrasound waves.

Infrasound waves are longitudinal waves (1) with a frequency less than 20 Hz (1)

Compared to normal sound waves, infrasound waves always have a smaller

frequency

Name a use of infrasound Communication between animals, detection of animal movement in remote places, detection of volcanic eruptions and meteors

Explain which is the best type of sound wave for whales to use when communicating over long distances

Infrasound (1) is the best type of sound for whales communicating because it decreases in amplitude is least (1) and can be detected/'heard' further away (1)

Describe what happens at the plate boundary to cause an earthquake.

An earthquake occurs when a plate moves/slip (1) causing a sudden release of energy (1)

Explain what causes the plates to move. Plates move due to heat from the Earth’s core (1) which causes convection currents (1) in the mantle (1)

The instrument used to detect earthquakes is a Seismometer

Earthquakes produce P-waves and S-waves. Describe what can happen to these waves when they reach the boundary between the crust and the mantle

When P-waves or S-waves meet the boundary between the crust and mantle, they can be reflected (1) and refracted (1)

Waves from an earthquake are examples of… …both transverse and longitudinal waves

Describe how particles in the ground move when P-waves pass through it.

Particles in P-waves vibrate (1) in same direction as wave/energy moves (1)

What can P-waves travel through? P-waves can travel through solid and liquid at speeds of about 10km/s. So these waves can travel from one side of earth through to the opposite point.

What can S-waves travel through? S-waves can travel through solids but NOT liquids at speeds of about 6km/s. So these waves cannot travel through the liquid outer core of the earth and cannot be detected at the opposite point on the earth.

Explain what causes a tsunami Tsunamis are caused by underwater earthquakes / volcanic eruption (1) and are random (1)

Explain why scientists find it difficult to predict when a tsunami may happen.

Because it is impossible to predict earthquakes (1) as there is no pattern to when movements occur (1) and they are not able to predict force needed to make tectonic plates move (1).

Geologists use sound waves from a small explosion to search for oil underground.

Seismic waves

A small explosion is triggered at the Earth's surface. The waves reflect back from the top of the oil field. Suggest why the waves are reflected from the oil field.

Because there is a difference/change in density (1)

P1 Topic 5 Core Questions What is the difference between current and voltage? Current is the ‘rate of flow of charge’ and voltage is the

‘electrical pressure giving a measure of the energy transferred’.

An electric current is the rate of flow of Charge

State the unit in which electric current is usually measured. Ampere(s), amp(s), A

Describe what happens inside a generator to produce a current.

A magnet (1) spins/turns (1) in/near) a coil of wire (1) OR A coil of wire (1) spins/turns (1) in a magnetic field

State one way in which the size of the current could be increased.

You can increase the size of a current by increasing the strength of magnet (1); increasing number of coils/turns of wire (1) or increasing the speed of rotation (1)

A generator is connected to a lamp. The generator is turned faster. Explain what happens to the lamp.

The light bulb would increase in brightness (1), due to an increased voltage (1)

Describe the difference between direct current and alternating current.

With direct current the flow of charge is only in one direction (1) whereas with alternating current the flow of charge changes (1)

State the difference between the currents which makes one alternating and the other direct.

Alternating current can take positive and negative values RA (1)

What is the name of the device used to change the size of an alternating voltage?

Transformer

The output from the solar panel is 60 V. State why a transformer cannot be used to increase this voltage.

Transformers only change alternating voltages/currents and will not work with direct current

Describe what change happens when a step-up transformer is used.

As the voltage increases (1) the current decreases(1)

Why is electrical energy transmitted at high voltages? It improves efficiency by reducing heat loss in the transmission lines by allowing a lower current to be used.

Where would step up and step down transformers be used in the national grid?

Step up transformers are used in power stations whereas step down transformers are used before electricity enters factories and again before it enters homes, offices and shops.

What unit is electrical energy from the mains measured in? Kilowatt-hours

What is power and what units is it measured in? It is the rate of transferring energy. It is measured in Watts (W).

What are the standard units for energy transferred? Joules (J)

A small notebook computer has a power rating of 40 W. How much energy is supplied to the computer each second?

40J

Describe how electrical energy is obtained from one named renewable resource.

Any of the following: Hydroelectric Geothermal Wind turbine

One type of solar panel uses the Sun's energy to produce electricity. Which energy transfer takes place in a solar cell?

Light to electrical

What is a renewable and non-renewable energy source? Non-renewable: Once it has been used it has been effectively lost. (Examples include coal, oil and gas (fossil fuels) and uranium.)

Renewable: It can be used again and again. (examples include: wind, wave, solar, geothermal, hydroelectric, bio fuels etc.)

What are the advantages of non-renewable sources of energy?

Possible to generate large amounts of electricity reliably and relatively cheaply.

What are the disadvantages of renewable sources of energy? Not always reliable, often expensive, don’t generate a lot of electricity in comparison to non-renewables.

P1 Topic 6 Core Questions Name 9 different types of energy. Light, thermal (heat), sound, electrical, Kinetic (movement),

chemical, gravitational potential, elastic potential, nuclear.

The athlete gets the energy he needs for his jump from his food. The form of energy stored in food is

Chemical energy

Which forms of energy does the athlete have at the top of his jump?

gravitational potential and kinetic

Describe the energy transfer taking place in a loudspeaker.

A loudspeaker transfers electrical energy (1) into sound energy (1)

A student uses a solar powered battery charger to charge some batteries. What is the form of energy transferred into the battery charger?

light energy → electrical energy → chemical energy (1)

Can energy be created? No, it can only be transferred. Energy is conserved.

The students read the statement: ‘All the energy supplied to the motor eventually ends up as thermal energy in the surroundings.’ This statement best describes the idea of…

conservation of energy

Some students investigate the efficiency of electric motors. One of the students states that all of the energy supplied to a motor is transferred into other forms. This statement is one example of the idea of

conservation of energy

What is efficiency? A measure of how much of the energy is transferred into a useful energy type.

How does a system remain at a constant temperature? It needs to radiate the same average power (measured in Watts (W)) as it absorbs.

When the heater is switched on, it quickly warms up and then stays at a constant temperature. Explain why the heater stays at a constant temperature.

An explanation linking dissipating heat (1) at same (rate)/s quickly as energy is being supplied (1)

The electric motors which drive the wheels are painted black. Suggest why the motors are painted black

Any one from black is a good thermal radiator (1) (helps to) prevent motors overheating (1)

State why the pipes in the solar water heater are painted black.

Black is a good absorber of heat energy (1) as it absorbs more infrared radiation (1)

The hosepipe is painted black because blackened surfaces are…

…good absorbers of radiation

A solar powered shower uses a plastic bag containing water; the instructions are to leave the bag out in sunlight during the day. Explain what colour the bag should be to heat the water to the highest temperature.

The bag should be black (1) because black is a good absorber of thermal radiation (1)

P1 Keywords and Definitions

keywords Definitions

Converge When rays of light come together towards a point.

Converging Lens A lens which focuses light inwards onto a point. Also called convex.

Convex Lens A lens which focuses light inwards onto a point. Also called converging.

Eyepiece lens The lens found in the place you look into on a telescope.

Focal length The distance between lens and focussed image.

Geocentric Earth at the centre.

Heliocentric The Sun at the centre.

Image The visable reproduction of an object, e.g. by a lens.

Interface The point where two things interact or meet.

Lens An object that refracts light in a way that makes it diverge or converge.

Light waves The name given to waves in the EM spectrum that we can see.

Magnifications Enlargements.

Magnified Made bigger by a lens.

Magnify To enlarge an image.

Microwaves The waves in the EM spectrum that can be used for heating water and sending signals.

Naked eye The body part that can be used to look into the night sky.

Normal The imaginary line at right angles to a surface.

Objective lens A lens which magnifies the image.

Orbits The curved path an object follows around another object in space.

Primary mirror The curved mirror in a telescope that light first reflects off.

Radio waves The name given to waves in the EM spectrum that have the longest wavelength.

Real image An image which can be projected onto a screen.

Reflected "Bounced" off a surface.

Reflecting telescope A telescope that uses a curved mirror and lens.

Refracting telescope A telescope which uses lenses and not mirrors.

Refraction The name given to light changing speed and direction between two materials.

Telescope A device used to study space.

Transfer Move from place to place.

Transverse waves Waves where the movement is at right angles to the direction of travel.

Virtual image An image which appears to exist if you look through a lens but you cannot project.

Visible light The part of the electromagnetic spectrum that we can see.

Alpha (α) particles Helium nuclei (2 protons and 2 neutrons).

Amplitude The "height" of a wave or how much it is displaced.

Beta (β) particles High speed electrons.

DNA An acid which makes up a code that gives us our genetics.

Electromagnetic radiation Any emitted part of the EM spectrum.

Electromagnetic spectrum

The spectrum of light - visible and not visible.

Electromagnetic waves "Light waves" found anywhere in the EM spectrum.

Fluorescence Giving off light.

Fluorescent lamps A lamp that gives off light.

Frequency How many waves pass per second.

Gamma rays The region of the spectrum that kills cells and can be very harmful.

Hertz (Hz) The unit for frequency meaning once per second.

Illuminated Lit up.

Infrared The region of the electromagnetic spectrum that is produced by all objects with heat.

Infrared radiation (IR) The region of the electromagnetic spectrum that is produced by all objects with heat.

Ionising radiation Radiation that can cause particles to gain a charge by losing electrons or an electron.

Ions A particle with a charge (due to an unbalanced number of electrons).

Longitudinal waves Waves where the movement is along the direction of travel.

Mutations When the DNA of a cell is altered.

Negative powers A power in maths that has a negative value.

Optical fibre A glass strand that can allow light to pass through it.

Radioactive Something which gives off ionising radiation.

Radiotherapy Treating someone with radiation.

Seismic waves Waves created by earthquakes.

Skin cancer An illness caused by mutations in skin cells.

Sound waves Waves generated by noise.

Thermal imaging Making an image based on the heat given off by something.

Ultraviolet The region of the electromagnetic spectrum that is next to violet but can't be seen.

Ultraviolet radiation (UV) The region of the electromagnetic spectrum that is next to violet but can't be seen.

Vacuum A space with no particles in it.

Wave speed The speed of the wave.

Wavelength The length of a wave.

X-rays The region of the spectrum used to take medical images of bones.

Big Bang theory The idea that the Universe quickly expanded from a point in space and no new matter is created.

Black hole A dead star creating so much gravitational pull that even light is pulled in.

Cosmic microwave background (CMB) radiation

Radiation found evenly spread throughout the Universe.

Dense Tightly packed.

Doppler Effect The effect heard when an ambulance comes towards you then moves away.

Fusion reactions A reaction where hydrogen become helium and releases energy (like in stars).

Galaxy A collection of millions of stars that are close together and possibly orbit a black hole.

Landers Something which goes to another planet.

Main sequence The normal life cycle a star follows.

Milky Way The galaxy in which we live.

Nebulae Huge clouds of gas in space.

Neutron star A dead star that is very dense.

Nuclei The centres of things (including atoms).

Pitch Effectively means frequency.

Protostar The beginnings of a new star.

Red giant A main sequence star that is getting older and bigger.

Red supergiants A larger star that is getting older and bigger.

Red-shift When light looks more red because of a stretched wave length.

Rovers Something which moves around on another planet.

Search for Extraterrestrial Intelligence (SETI)

A project that searches for intelligent life in space.

Solar System A collection of stars and planets in orbit of each other.

Space probes Something which we send into space looking for things.

Spectrometer Something that measures a spectrum, looking for dark lines in it.

Spectrum In terms of light this means all of the groups of light. It can mean a rainbow.

Stars Balls of gas in space that emit light due to the nuclear reactions within them.

Steady State theory The idea that the Universe has always existed but gets bigger with new matter being made.

Supernova A huge explosion from a dying star.

Universe Everything that exists.

Visible light The light which we can see.

White dwarf The remnants of a dead main sequence star.

Convection currents The way in which heat "moves" in the mantle, rising and falling.

Core The centre of the Earth.

Crust The outer layer of the Earth made up of rock.

Earthquakes A tremor resulting from movement in the Earth's crust.

Epicentre The point at the surface directly above the focal point of an earthquake.

Focus The point where a seismic wave began.

Frequency How many waves pass in a second.

Infrasound Low frequency sound (below 20Hz).

Mantle The layer below the Earth's crust made of molten magma.

Medium A material through which something passes.

P waves Longitudinal (and faster) seismic waves.

Refracted Waves that have changed speed and direction at the boundary between two materials.

S waves Transverse (and slower) seismic waves.

Seismic waves A wave which travels through the Earth.

Seismometers A device used to measure the size of waves travelling through the Earth.

Sonar A system used to see how deep water is (or look for objects in water).

Sound wave A wave caused by noise.

Tectonic plates The large area of the Earth's crust that move slowly.

Tsunami Water waves caused by movement in the Earth's crust.

Ultrasound High frequency sound (above 20,000Hz).

Ultrasound scan A scan using high frequency sound waves.

Acid rain Rain with a lower pH.

Alternating current (AC) Current which flows "back and forth" or in different directions.

Carbon brushes Connectors used to maintain a good contact with the dynamo as it spins.

Climate change The change to the temperature and weather of the Earth.

Current The flow of charge/electrons.

Decommissioned Not used any more and shut down/disused.

Direct current (DC) Current which flows in one direction only.

Dynamos A device which used movement (kinetic energy) to create electricity.

Efficiency How much energy is transferred usefully compared to how much is wasted.

Electricity The flow of charge/electrons, often in a wire.

Electromagnetic induction

The creation of electrical current by moving a magnet along/around a wire.

Electromagnets A magnet created using an electrical current.

Fossil fuels Fuels from fossilised plants and animals (coal, oil and natural gas).

Generator A device which produces electricity.

Geothermal energy Energy from hot rocks beneath the Earth's surface.

Hydroelectricity Electricity produced by water turbines in dams of reservoirs.

Induced current Current created by a magnetic field being moved along a wire (like in a dynamo).

Joule (J) The measurement of energy.

Kilowatt-hour (kWh) A measurement of electricity use in a home meaning 1000W being transferred in an hour.

Kilowatts (kW) A thousand watts (1000W).

Magnetic field A field caused by a magnet with a north and south.

National Grid The wires and transformers that supply electricity around the country.

Non-renewable resources Energy resources from sources that cannot be replenished (can run out).

Nuclear power Energy from nuclear materials like uranium.

Power The rate (speed) at which energy is transferred.

Primary coil The coil of wire carrying electrical current entering a transformer.

Renewable energy resources

Energy that comes from a source that is continually replenished (isn't running out).

Secondary coil The coil of wire carrying electrical current leaving a transformer.

Slip rings Connection rings found on a dynamo.

Solar cells A cell that produces electrical current when sunlight is absorbed by it.

Solar energy Energy that comes from sunlight.

Step-down transformer A device which decreases the voltage of AC current.

Step-up transformer A device which increases the voltage of AC current.

Tidal power Energy from the rising and falling tide.

Transformer A device which changes the voltage of AC current.

Unit The measurement of electricity use in a home.

Voltage The "pressure" in a circuit, sometimes called the potential difference.

Watt (W) The unit for power, also meaning joules per second.

Wave power Energy from waves.

Wind turbines Turbines that are turned by the wind (like windmills).

Chemical potential Energy potential in chemicals.

Cost-efficient Pays for itself with the savings it makes.

Elastic potential Energy potential in something elasticated.

Electrical Energy which is the flow of electrons.

Energy transfer The change of energy from one for to another.

Gravitational potential Energy potential as you move up through gravity or higher.

Kinetic Movement energy.

Law of conservation of energy

The law that energy is never lost.

Light The form of energy we see.

Nuclear potential Energy potential in radioactive materials.

Payback time The time it takes for the savings of a new device to cover the cost of buying it.

Sound Energy we hear.

System Connected processes that make up a bigger whole.

Thermal Heat energy.

P2 Core Questions Topic 1

Name 3 sub atomic particles Protons, neutrons and electrons,

Name the mass and charge of a proton Mass 1, charge positive

Name the mass and charge of an electron Mass 0, charge negative

Name the mass and charge of a neutron Mass 1, charge neutral

What sub-atomic particles are found in the nucleus? Protons and neutrons

What sub-atomic particles are found in orbits outside the nucleus?

Electrons

Opposite/unlike charges... Attract

Same/like charges... Repel

Describe how static electricity is formed Friction between 2 insulators causes electrons to move from one material to another.

What charge does an object which has gained electrons have?

Negative

What charge does the object which has lost electrons have? Positive

Explain how static electricity induces a charge A negative object is brought near a neutral object; it repels the negative electrons leaving a positive charge on the neutral object. The negative object is attracted to the now positive object.

Name 3 uses of static electricity

Spray painting cars, chimney precipitators, spraying insecticide

Describe how static electricity is used to spray paint (charges can be the other way around) Paint is given a negative charge; they repel each other and form a mist of paint. The car is given a positive charge; the negative paint attracts to the positive car and coats it.

Suggest benefits to using static electricity for spray-painting or insecticides

Less waste of paint Saves money

Explain how static electricity builds up in aircraft Friction, caused by the plane colliding with particles in the atmosphere, causes electrons to build up in the body of the aircraft as it is insulated and these electrons cannot be earthed.

What are some of the potential dangers of electrostatic charges?

-Fuelling aircraft- static builds up in the nozzle and could spark and ignite the fuel causing an explosion -Lightning -Flying aircraft

How are aeroplanes refuelled safely The aeroplane and the tanker are earthed using a metal wire to discharge any build up of electrons

Describe the movement of electrons when you get a static electric shock

Electrons are built up in you as your shoes/jumper rub against something, when you touch a conductor you get an electric shock as electrons flow from you through the conductor and to the Earth.

Why are metals good conductors? They contain a sea of delocalised/free electrons, which are free to move

What is current? The flow of electrons

What is electric current? The rate of flow of electrons

Describe a direct current The flow of electrons in one direction

State objects that would produce a direct current A battery, a cell, a dynamo

Describe an alternating current Electrons moving back and forth millions of times a second

How do you calculate charge? Charge = current x time

What unit do we measure charge in? Coulombs (C)

Topic 2

What is the unit for current, how do you measure it and how do you place it in a circuit?

Measured in Amps (A), using an ammeter which is placed in series in a circuit

What is the unit for potential difference, what equipment do you use to measure it and how do you place it in a circuit?

Measured in Volts (V), using a voltmeter which is placed across a component (parallel to a component)

What happens to current in a series circuit? The current is always the same throughout a series circuit

What happens to the voltage in a series circuit? The voltage provided by the power pack/battery is shared between the components in the series circuit

If the potential difference across V2 is 2.5V and across V3 is 2.5V, what is the potential difference across V1?

5V V1 = V2 + V3

If A1 read 3A, what would the current at A2 and A3 be?

3A

What happens to the current in a parallel circuit? The current splits/divides at a junction and recombines at a later junction

What happens to the voltage in a parallel circuit? The voltage across the powerpack/battery is the same across all components in a parallel circuit

If A1 = 3 A and A2 = 1A, what is the current measured at A3 and A4?

A3 = 2A A4 = 3A (because the current after the junction must always equal the current before the junction)

If V2 has the potential difference of 5V, what is the potential difference of V1 and V3?

They are both 5V

What happens to the current if you increase the potential difference (voltage) of a power pack/battery

The current increases

If you increase the resistance in a circuit, what happens to the current?

It decreases.

How do you calculate resistance? Resistance = voltage / current R = V/ I

What is the unit for resistance? Ohms (Ω)

Determine the resistance of this circuit if the current is 2.5A and the voltage is 3V

Equation: R = V/ I Substitute: R = 3V / 2.5A Calculate: 3 / 2.5 = 1.2 Units: R = 1.2 Ω

If the current in a circuit is 1.4A, and the resistance is 3Ω, what is the potential difference in the circuit?

Equation: V = I x R Substitute: V = 1.4A x 3Ω Calculate: 1.4 x 3 = 4.2 Units: V = 4.2V

Figure out the current when the resistance is 2.5Ω and the voltage is 13V.

Equation: I = V / R Substitute: I = 13V / 2.5Ω Calculate: 13 / 2.5 = 5.2 Units: I = 5.2A

Explain why the resistance of a filament lamp changes as it gets hot?

The resistance of a filament lamp increases as it gets hot because the metal ions in the filament vibrate faster causing more collisions with the moving electrons, decreasing current.

How does a diode work? It only allows current to pass through it in one direction.

How does the current vary with voltage for a diode? When the current is flowing in the right direction, the current increases voltage increases but it is not directly proportional (not a straight line on the graph). The gradient of the graph increases as current increases, because as the diode gets hotter (from the greater current) its resistance increases.

What is an LDR? Light dependent resistor.

How does the resistance of a light dependant resistor change with light intensity?

As light intensity increases, the resistance decreases.

What happens to the resistance and current in a thermistor as you increase temperature?

As the temperature increases, the resistance decreases, which increases the current (flow of electrons)

How does the current vary with voltage for a filament lamp as it warms up?

As a bulb heats up the resistance increases and so, as current increases voltage increases but it is not directly proportional (not a straight line on the graph). The gradient of the graph increases as current increases. This is because as the bulb gets hotter its resistance increases, until it reaches its maximum temperature.

Which of the following graphs shows how current varies with potential difference for:

1) Filament lamp 2) Diode 3) Fixed resistor

1) Filament lamp – graph a 2) Diode – graph c 3) Fixed resistor – graph b

What does resistance transfer electrical energy into? Thermal energy (heat)

Name a device where the heating effect of an electric current is useful.

Toaster, kettle, oven...

Name a device where the heating effect of an electric current is not useful.

Light bulb

What is the unit for electrical power? Watt

What is the unit for energy transferred? Joule

What is power? The rate of energy transferred from one form to another/others.

What unit do we measure power in? Watts (W)

How can you calculate power using the energy transferred in an object and the time it is used for?

Power = Energy transferred/time taken P = E / t

What is the power of a device if it transfers 18,000J of energy in 10 minutes?

Equation: P = E / t Convert: time needs to be in seconds, 10 minutes x 60 = 600s Substitute: P = 18,000J / 600s Calculate: 18,000 / 600 Units: P = 30W

How long is a 50W device used for if it transfers 1.5kJ? Equation: t = E / P Convert: Energy needs to be in J: 1.5kJ x 1000 = 1500J Substitute: t = 1500J / 50W Calculate: 1500 / 50 = 30 Units: t = 30s

How much energy is transferred when a 500W device is used for half an hour?

Equation: E = P x t Convert: Time needs to be in seconds: 0.5 hours x 60 = 30 minutes x 60 = 1800s Substitute: E = 500W x 1800s Calculate: 500 x 1800 = 900,000 Units: E = 900,000J

How can you calculate power using current and voltage? Power = Current x voltage P = I x V

A kettle uses the mains electricity at 230V. The current is 13A. What is the power of the kettle?

Equation: P = I x V Substitute: P = 13A x 230V Calculate: 13 x 230= 2990 Units: P = 2990W

What is the current flowing through a 36W device using a 12V power supply?

Equation: I = P / V Substitute: I = 36W / 12V Calculate: 36 / 12 =3A Units: I = 3A

What is the voltage of the power supply for a 144W device which has current of 16A flowing through it?

Equation: V = P / I Substitute: V = 144W / 16A Calculate: 144 / 16 = 9 Units: V = 9V

How is energy calculated using an equation? (hint: combine the power calculations together!)

Energy = Current x Voltage x time E = I x V x t

What is the energy transferred when a radio uses a 12V supply for 15 minutes, and has a current of 3A?

Equation: E = I x V x t Convert: 15 minutes into seconds: 15 x 60 = 900s Substitute: E = 3A x 12V x 900s Calculate: 3 x 12 x 900 = 32400 Units: E = 32400J

Topic 3

What is the unit for velocity? m/s

What is a vector quantity? It has both a size (magnitude) and direction.

Give 5 examples of a vector quantity? Displacement, velocity, acceleration, force and momentum.

How is speed calculated? Speed = distance / time

A cyclist travels a distance of 1800m in 2 minutes. What is their speed? Equation: S = D / t Convert: Time needs to be in seconds: 2 x 60 = 120s Substitute: S = 1800m / 120s Calculate: S = 1800 / 120 = 15 Units: S = 15 m/s

How long did it take for a car to travel 30 metres when travelling at 0.6m/s?

Equation: t = D / S Substitute: t = 30m / 0.6m/s Calculate: t = 30 / 0.6 Units: t = 50s

A peregrine falcon can fly at speeds of 50m/s, at this speed how far can it travel in 7 seconds?

Equation: D = S x t Substitute: D = S x t Calculate: 50 x 7 = 350 Units: 350m

Using a distance time graph, describe what is happening to the object between O and A, A and B and B and C?

O and A: The object is accelerating forwards A and B: The object is stationary B and C: The object is moving backwards

What is acceleration and its unit? Acceleration is the rate of change of speed, its unit is m/s2

How do you calculate acceleration? Acceleration = change in velocity / time

How do you calculate change in velocity? Change in velocity = final velocity – initial velocity v – u

A car starts from 0m/s and reaches a velocity of 50m/s in 5 seconds, what is its acceleration?

Equation: A = (v – u) / t Substitute: A = (50m/s – 0m/s) / 5 Calculate: A = 50 / 5 Units: 10 m/s2

What is the change in velocity if an object accelerates at a rate of 2m/s2 in 600 seconds

Equation: (v – u) = A x t Substitute: (v – u) = 2m/s2 x 600s Calculate: 2 x 600 = 1200 Units: (v – u) = 1200m/s

How long did it take for a car accelerating by -2.5m/s2 when its initial velocity was 70m/s and its final velocity was 20m/s.

Equation: t = (v – u) / A Substitute: t = (20m/s – 70m/s) / -2.5m/s2 Calculate: -50 / -2.5 = 20 Units: t = 20s

Give 2 examples of how an object can accelerate. 1) If it’s speeding up or slowing down. 2) If it’s changing direction.

Describe the motion of each objects on these velocity-time graphs

1) The object is accelerating quickly 2) The object is moving at a constant speed 3) The object is decelerating 4) The object is stationary

Describe how to calculate the distance an object has travelled using a velocity-time graph

By measuring the area under the graph

Name a force Friction/drag/air resistance/water resistance Weight/gravity Thrust/upthrust/ Reaction Lift

When 2 forces (action and reaction forces) interact with each other, what effect do they have?

When action and reaction forces interact they exert a force that is equal in size and opposite in direction to each other

Describe the motion of each 4 objects

A: Stationary B: Accelerating C: Constant speed D: Decelerating

What are the forces in this free-body diagram?

1= reaction 2= gravity

What are the forces in this free-body diagram?

1= reaction 2= thrust 3= gravity 4= friction/air resistance/ drag

If the forces acting on an object are balanced and the resultant force is zero, what is the motion of the object?

Stationary or constant speed

If the forces on an object are unbalanced, how will it behave? It will accelerate in the direction of the resultant force.

What is resultant force? The total force that results from 2 or more forces acting on an object

What is the resultant force of this object? What is it’s motion?

10N to the left The object is decelerating

A cyclist applies 100 N of thrust to a bike and is battling against 75 N of wind resistance, how would you describe their motion and what is the resultant force?

They are accelerating with a resultant force of 25N acting in forwards direction.

What 2 factors affect the size of the acceleration of an object? The mass of the object and the size of the force accelerating the object forwards

F=ma what does it stand for, what are the units for F and m? Force = mass x acceleration Force unit is Newtons (N) Mass unit is kilograms (Kg)

A 1500kg car has an acceleration of 3.0m/s2, what is the force provided by the engine?

Equation: F = M x A Substitute: F = 1500kg x 3m/s2 Calculate: 1500 x 3 = 4500 Units: F = 4500N

A car accelerates at 6m/s² as its engine provides a force of 7,800 N. What is the mass of the car?

Equation: M = F / A Substitute: M = 7,800N / 6m/s2 Calculate: M = 7,800 / 6 Units: M = 1,300kg

A jumbo jet has a mass of 40, 000,000g. If its engines produce a force of 800, 000 N, what will its acceleration be?

Equation: A = F / M Convert: Mass needs to be in kg, 40,000,000 / 1000 = 40,000 Substitute: A = 800,000 / 40,000kg Calculate: 800,000 / 40,000

Units: A = 20m/s2

What is the difference between mass and weight? Mass never changes, it is a measure of the amount of matter that makes up an object whereas weight depends on the gravitational field strength of a planet

What is terminal velocity? The point at which the weight and air resistance are balanced and the object can accelerate no more.

Describe how the forces acting on a ball change as it starts to fall from the sky

At the start of the fall the downward force (weight) is greater than the upward force (air resistance). The weight remains constant but the air resistance increases as the ball accelerates until the weight is balanced out by the air resistance. At this point the ball is moving at a constant speed, this is known as the terminal velocity.

How do you calculate the weight of an object? Weight (N) = mass (kg) x gravitational field strength (N/kg)

What is the weight of a 300kg planetary landing craft on the surface of the Earth?

Equation: W = M x GFS Substitute: W = 300kg x 10N Calculate: 300 x 10 = 3000 Units: W = 3000N

What is the mass of an object if the weight is 120N on Jupiter whose GFS is 25N/kg?

Equation: M = W / GFS Substitute: M = 120N / 25N/kg Calculate: M = 120 / 25 = 0.48 Units: M = 4.8kg

What is the GFS of Mars if a 150kg object has a weight of 570N? Equation: GFS = W / M Substitute: GFS = 570N / 150kg Calculate: 570 / 150 = 3.8 Units: GFS = 3.8N/kg

Topic 4

How do you calculate the stopping distance of a car? Stopping Distance = Thinking distance + Braking distance

List four factors that affect the thinking distance of a driver alcohol/other drugs, tiredness, distractions, age,

List 5 factors that affect the braking distance of a car Quality of brakes, mass of vehicle, speed of vehicle, state of the road, the amount of friction between the tyre and road surface (affected by weather and tyre condition).

What is momentum? Momentum is a measurement of the velocity and mass of a moving object.

Name 3 ways we can change the momentum of an object 1. Changing the size of an object 2. Changing the speed of an object 3. Changing the direction of an object

What is the unit for momentum? Kg m/s

How do you calculate momentum? Momentum = mass x velocity

A 1200kg car travels along at 12 m/s, calculate its momentum.

Equation: Mo = Ma x V Substitute: Mo = 1200kg x 12m/s Calculate: Mo = 1200 x 12 = 14400 Units: Mo = 14,400 kg m/s

Calculate the velocity of a 250kg object if it’s momentum is 5000 kg m/s.

Equation: V = Mo / Ma Substitute: V = 5000 kg m/s / 250kg Calculate: V = 5000 / 250 = 20 Units: V = 20 m/s

Calculate the mass of an object which has the momentum of 54, 000 kg m/s and travels at a velocity of 12m/s.

Equation: Ma = Mo / V Substitute: Ma = 54,000kg m/s /12m/s Calculate: Ma = 54,000 / 12 = 4500 Units: Ma = 4500 kg

What features do cars have to reduce the rate of change of momentum of passengers when the car brakes sharply or has a collision?

Seatbelts, crumple zones, air bags.

Why do seat belts, crumple zones and air bags make collisions safer?

They increase the time taken for the person in the vehicle to stop; this reduces the size of the force acting on a person.

What is the law of conservation of momentum? The total momentum before a collision is the same as the total momentum after a collision

A ball with momentum of 10kg m/s hits a stationary object, what is the total momentum of the balls after the collision?

10kg m/s

HIGHER) How can you calculate the force of an object during a collision?

Force = Change in momentum / time

HIGHER) What force is needed to get a 25 kg stationary bicycle moving from 0m/s to 12 m/s in 5s?

Momentum at start = 0 × 12 = 0 kg m/s Momentum at end = 25 × 12 = 300 kg m/s Change in momentum = 300 – 0 = 300 kg m/s Equation: Force = change in momentum ÷ time Substitution: Force = 300kg m/s ÷ 5s Calculation: Force = 300 ÷ 5 = 60 Units: Force = 60N

How can you increase an objects gravitational potential energy?

Increase the objects height

How do you calculate work done? Work done (J) = Force (N) x Distance (m)

What is work done? It is the amount of energy transferred

What is the unit for work done? Joules

Sharon lifts a 5N weight 50cm, how much work is done? Equation: WD = F x D Convert: distance needs to be in metres= 50cm becomes 0.5M Substitute: WD = 5N x 0.5 Calculate: 5 x 0.5 = 2.5 Units: WD = 2.5J

What is the force if the work done is 30J when an object is moved 4m?

Equation: F = WD / D Substitute: F = 30J / 4m Calculate: 30 / 4 = 7.5 Units: F = 7.5N

Calculate the distance an object when it is moved with a force of 30N, if the work done is 900J.

Equation: D = WD / F Substitute: D = 900J / 30N Calculate: 900 / 30 = 30 Units: D = 30m

What is a definition of power? The amount of energy transferred every second (Joule per second (J/S))

What is the unit for power? Watt (W)

How do you calculate power? Power = work done / time

What can be measured in joules per second? Power

The rate of doing work is called... Power

Calculate the power of an object if the work done is 800J in 400s

Equation: P = WD / t Substitute: P = 800J / 400s Calculate: 800 / 400 = 2 Units: P = 2W

What is the work done if a 500W crane moves a box in 1,800s?

Equation: WD = P x t Substitute: WD = 500W x 1,800s Calculate: 500 x 1,800 = 900,000 Units: WD = 900,000s

How fast can a 1,600W machine move an object which would require 32,000J?

Equation: t = WD / P Substitute: t = 32,000J / 1,600W Calculate: 32,000 / 1,600 = 20 Units: t = 20s

How can you combine work done = force x distance and power = work done / time

Power = (force x distance) time

A motorbike accelerates over 40m, it uses a force of 6000N and takes 5 seconds to travel the 40m. What power did the engine produce?

Equation 1: Work done = F x d Substitute: Work done = 6000N x 40m Calculate: Work done = 240,000 J Equation 2: Power = work done / time taken Substitute: Power = 240,000J / 5 Calculate: Power = 240,000 / 5 = 48,000 Units: Power = 48,000W or 48kW Or Equation: P = (F x D) / t Substitute: P = (6000 x 40) / 5

Calculate: 240,000 / 5 = 48,000 Units: 48,000W

A cart on a rollercoaster sits stationary at the top of a steep drop. Which type of energy does it have a lot of?

Gravitational Potential Energy (GPE)

What is the value of this energy equal to? The work done moving the cart to the top of the ride.

As the cart rolls down the track, what is this energy converted to?

Kinetic, thermal (heat) and sound energy

Name 9 different types of energy. Kinetic, gravitational potential, electrical, chemical, nuclear, sound, light, heat, elastic

Energy transfers are never totally efficient, which type of energy is most often lost to the surroundings in an energy transfer?

Heat

At which point will the ball have the maximum/greatest gravitational potential energy?

B has the greatest gravitational potential energy

What energy changes are occurring between B and C?

Gravitational potential energy is decreasing as it transfers into an increasing amount of kinetic energy, thermal energy and sound energy

How do you calculate gravitational potential energy? GPE (J) = mass (kg) x gravitational field strength (N/kg) x height (m)

What is the gravitational potential energy gained by a 500kg car is lifted 15m on Earth (GFS=10N/kg)?

Equation: GPE = m x gfs x h Substitute: GPE = 500 x 10 x 15 Calculate: 500 x 10 x 15 = 75000 Units: GPE = 75,000 J

How do you calculate kinetic energy? Kinetic energy = ½ x mass x velocity2

What is the kinetic energy transferred by a 2kg dog walking 2m/s?

Equation: KE = ½ x m x v2 Conversions: 2m/s x 2m/s = 4m/s2 Substitute: KE = ½ x 2kg x 4m/s2 Calculate: KE = 0.5 x 2 x 4 Units: KE = 4J

Topic 5

What is alpha radiation? A Helium nuclei (two protons and two neutrons)

What is beta radiation? An electron

What is gamma radiation? An electromagnetic wave

What is an ion? A charged atom or group of atoms.

How do atoms form ions? By gaining or losing electrons.

When an unstable nucleus emits ionising radiation is it a random or predictable event?

random

Which is most highly ionising type of radiation? Alpha

Which is more penetrating type of radiation? Gamma

For each type of radiation, state what can stop it Alpha: a sheet of paper, skin, a few cms of air Beta: 3mm aluminium, metres of air Gamma: Thick lead or concrete; kilometres of air

What is the atomic number? The number of protons present.

What is the mass number? The relative mass of an atom which is equal to the number of protons and neutrons present.

What is an isotope? Two or more atoms of the same element (the same number of protons) but with a different number of neutrons.

Do radioactive sources stay radioactive forever? No- the activity of a radioactive source decreases over time

Describe how nuclear fission produces thermal energy 1) Uranium 235 nucleus absorbs a neutron 2) Nucleus becomes unstable 3) Nucleus splits (known as fission)

4) Into 2 daughter nuclei (of similar size) (Kr & Ba) 5) 2 or more neutrons released 6) Energy is released

What is a nuclear chain reaction? Where the neutrons produced by a fission reaction trigger further nuclear fission reactions. This increases in number of fission reactions as more neutrons are produced.

What does the fission of U-235 produce? Two daughter nuclei and two or more neutrons and a large amount of energy.

How are chain reactions controlled? Control rods are lowered to absorb excess neutrons

How can you increase the amount of electricity being generated using the control rods in a nuclear reactor?

By moving the control rods out of the reactor, fewer neutrons are absorbed and so more fission reactions occur. This produces more thermal energy which enables more electricity to be generated

How can you stop a nuclear reactor fully? By lowering the control rods all the way to the bottom of the nuclear reactor, all neutrons produced by fission reactions will be absorbed and so no further reactions will occur, stopping the nuclear reactor from producing energy.

What does the moderator do in a nuclear reactor It slows neutrons down so they can be absorbed by a uranium nucleus and result in another fission reaction.

What material is used for a control rod? Boron

What material is used for a moderator? Graphite

What is the key benefits and disadvantages of using nuclear power to generate electricity?

Benefits: no direct CO2 emissions Disadvantages: public perception, risk, safety issues and radioactive waste disposal, use of nuclear materials in terrorism.

How is thermal energy from a nuclear reactor used to generate electrical energy in a power station?

Thermal energy from the nuclear reactor turns the water into steam. This turns a turbine which in turn turns a generator (a coil of wire inside a magnetic field), generating electricity.

What is nuclear fusion? Reaction caused when the nuclei of light atoms like Hydrogen join together to make the nucleus of a heavier atom like helium.

Describe what happens during nuclear fusion 2 hydrogen nuclei join/fuse together to form helium nuclei which releases thermal energy

Where is fusion found naturally? In stars

What are the conditions required for fusion and where does it normally occur?

At very high temperatures, very high pressures and densities, the hydrogen nuclei need to collide at very high speeds so they have lots of kinetic energy.

Why is it extremely difficult to initiate nuclear fusion? Both helium nuclei have positive charges This means they repel each other This reduces possibility of successful collisions to form helium, a neutron and also the energy The rate of fusion is too small to be useful for generating electricity.

Why can we not make a nuclear fusion power station? It is impossible to raise the temperature to the required level for enough reactant to make the reaction self-sustaining.

When is a new idea accepted by the scientific community (e.g. cold fusion)

When it can be validated

Explain the phrase validated by the scientific community. The procedure has been checked to confirm consistent results by other reputable scientists /organisations / peers.

Topic 6

What is the unit of activity of a radioactive isotope?

The Bequerel (Bq) is the number of emissions every second.

Why is ionising radiation dangerous? It can lead to tissue damage, burns, DNA mutations and cancer.

What precautions should be taken when handling radioactive substances?

Handle with tongs, protective clothing, never point a source at yourself or others. The risk is reduced with increased distance.

The nuclear power industry creates a lot of radioactive waste, what are the options for disposal?

Bury - probably best. Dump at sea - not preferable because over time the containers will corrode and leak radiation into the sea which could then get into the food chain.

Launch into space - expensive and not preferable because if the launch goes wrong it will scatter radioactive material over a large area of earth.

The products of nuclear fission are radioactive. Why is this problem?

Some remain radioactive for a many years. Long term storage and disposal is problematic.

What are some of the risks of using nuclear power? Rods are radioactive which can cause cancer Danger of accident during transport Workers could be exposed to radiation Can damage environment if not properly contained Materials being disposed of are radioactive for long periods of time Water causing corrosion / leaks of radioactive waste Security from terrorist activity Leakage of radioactivity Contamination of ground, sea water, lakes, rivers, crops, fish, animals, drinking water

What are some precautions we can take to reduce the risk of using nuclear energy to generate electricity?

Long term storage, underground /under the sea Radiation shielding, lead/steel/concrete/ containers, sealed in glass. Shielding to protect people from radiation Security can be used to prevent public access to nuclear power stations Vehicle transporting radioactive materials need to be protected against damage Special disposal facilities needed, not landfill sites Need to be kept secure while decaying to safe levels Some materials have a shorter half-life, so long term storage is not necessary

What are some of the advantages and disadvantages of nuclear power?

Advantages: +Nuclear power plants do not produce carbon dioxide Disadvantages: -Processes used to make fuel rods require energy and generating this energy may cause carbon dioxide to be produced -Nuclear waste has to be stored for tens of thousands of years, nothing can be leaked during this time -Nuclear power is considered unsafe as radioactive material can be spread over cities and towns thousands of miles away

What is half life? The time it takes for half the atoms in a radioactive sample to decay.

How can we calculate half life on a graph? 1) Identify the initial count rate (let’s say it is 80) 2) Divide this by 2 (80/2 = 40) 3) Draw a line on the graph from this value (40) 4) When you meet the line of best fit, draw a line to the x-axis 5) This is the half-life

A sample of air contains 6 mg of radon. Radon has a half-life of 4 days. Calculate the mass of the radon remaining after 8 days.

Calculation of number of half-lives: 8 ÷ 4 = 2 (half lives) Evaluation of mass: 6 ÷ 2 = 3 ÷ 2 = 1.5 (mg)

Where does background radiation come from? Radioactive rocks (earth), cosmic radiation (space), hospitals and industrial uses.

Why is radon gas a problem? Released from some rocks and increases background radiation in some regions of the UK

How do you measure the radioactivity of a sample? Take a reading of the background radiation (b) Measure the radioactivity of the sample (s) Subtract the background from the sample to get it’s radioactivity (r) R = b - s

The scientist takes several readings of background radiation. Explain why this is necessary to improve the accuracy of the investigation

More accurate Hard to measure a small activity Background radiation affects readings Need to find difference of two small quantities Can test smaller samples

Give 5 uses of radioactivity and say which type of ionising radiation is used in each.

1) Smoke alarms – alpha 2) Irradiating food – gamma 3) Sterilisation of equipment – gamma 4) Tracing and gauging thickness – beta 5) Diagnosis and treatment of cancer – gamma.

Explain why gamma radiation is used for sterilising equipment and irradiating food

Gamma radiation kills microbes/bacteria/viruses on equipment and food.

This prevents diseases being spread in hospitals and keeps food fresher for longer

Describe how smoke alarms work Alpha particles ionise air particles which completes the circuit in the smoke alarm. When smoke particles are produced, they absorb the alpha radiation which prevents the circuit from working and sets off the smoke alarm.

Explain how beta radiation is used to gauge thickness in materials

Beta radiation is passed between paper, if the paper is too thick it will absorb more beta radiation and the count rate being detected will decrease. This increases the pressure of the rollers which makes the paper thinner, allowing beta radiation to pass through it again. The opposite occurs if the paper is too thin.

Describe how gamma radiation is used to detect cancer.

Detect cancer: A tracer is taken by a person and is observed by a gamma camera. The gamma radiation shows areas of concerns and as it is very penetrating, the gamma radiation passes straight out of the body- it doesn’t stay inside the person which prevents damage to their body.

Describe how gamma radiation is used to treat cancers

Gamma radiation beams are targeted at cancerous cells from many angles to reduce radiating surrounding healthy cells. The radiation kills the cancer cells.

P2 Keywords and Definitions

Keyword Definition

Discharged To release a charge by a flow of electrons to earth (or neutral).

Earthing Many electrical appliances have metal cases, including cookers, washing machines and refrigerators. The earth wire creates a safe route for the current to flow through, if the live wire touches the casing.

Electrostatic charge The electric charge at rest on the surface of an insulated body (which establishes and adjacent electrostatic field).

Induced charge To make an object to become charged.

Induction The action by which a body possessing a charge of static electricity develops a charge of static electricity of the opposite character in a neighbouring body.

Neutrons A neutron is a subatomic particle contained in the atomic nucleus. It has no net electric charge, unlike the proton's positive electric charge.

Neutrons Particles in the nucleus with a mass of 1 and no charge,

Nucleus The central and most important part of an object, movement, or group, forming the basis for its activity and growth.

Protons A stable subatomic particle occurring in all atomic nuclei, with a positive electric charge equal in magnitude to that of an electron.

Static electricity A stationary electric charge, typically produced by friction that causes sparks or crackling or the attraction of dust or hair.

Alternating current In alternating current, the electrons don’t move steadily forward. Instead, they just move back and forth.

Ammeter An instrument for measuring electric current

Amperes (A) Equivalent to one coulomb per second, formally defined to be the constant current

Coulombs (C) The unit of electrical charge equal to the quantity of charge transferred in one second by a steady current

Current An electric current is a flow of electric charge through an electrical conductor.

Diodes Current will only flow through a diode in one direction only

Direct current An electric current that flows continuously in a single direction

Filament lamps As the temperature of the filament increases, the resistance increases making a curve.

In parallel When the components of a circuit are parallel to each other

In series when the components of a circuit are next to each other

Ions An atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

Light-dependent resistor (LDR) An LDR is a special type of resistor that changes its resistance depending on how much light there is

Ohms (Ω) Resistance unit

Parallel circuit A closed circuit in which the current divides into different paths before recombining to complete the circuit

Potential difference The difference of electrical potential between two points, measured in volts.

Power The rate at which work is performed, or energy converted.

Resistance Anything in the circuit which slows the flow down.

Series circuit A circuit that has its parts connected serially

Thermistors Similar to an LDR but its resistance depends on temperature, high temp low resistance and vice versa.

Variable resistor Controls the magnitude of resistance passing through the resistor

Voltage An electromotive force or potential difference (unit).

Voltmeter An instrument for measuring electric potential in volts.

Watts (W) The unit that measures power. Equal to one joule per second. A watt is equal to current x voltage.

Acceleration The rate of change of speed.

Action force A force that exerts a force on another object. It often comes in pairs with the Reaction Force, forming an action-reaction pairs.

Air resistance A force caused by air when an object is moving.

Displacement How far something has moved in a straight line.

Distance-time graphs A graph recording distance travelled over a particular time.

Drag A resistance to motion when an object moves through a medium. E.g. a boat moving through water.

Force Strength or energy as an attribute of physical action or movement

Free-body diagram A pictorial device, often a rough working sketch, used by engineers and physicists to analyse the forces and moments acting on a body.

Gradient How steep a line is.

Gravitational field strength Gravitational field strength at a point is defined as the gravitational force per unit mass at that point.

Interact Act in such a way as to have an effect on another

Mass The amount of an object there is.

Reaction force A force that acts in the opposite direction to an action force.

Resultant The result of two or more forces acting conjointly.

Speed How fast something is moving without a concern for the direction.

Terminal velocity Where the downward force of gravity equals the force of drag.

Vector A quantity that has a direction and size.

Velocity How fast something is moving in a particular direction.

Weight The force with which an object near the Earth or another celestial body is attracted toward the centre of the body by gravity

Air bags A safety device in a car, consisting of a bag that inflates automatically in an accident in order to increase the time it takes the person to slow down and reduce the force on their body.

Braking distance The braking distance is the distance taken to stop once the brakes are applied.

Crumple zones A part of a motor vehicle, esp. the extreme front and rear, designed to crumple easily in a crash and absorb the main force of an impact.

Crumple zones A part of a motor vehicle, esp. the extreme front and rear, designed to crumple easily in a crash and absorb the main force of an impact (by increasing the time it takes the vehicle to stop).

Energy transferred The amount of energy being transferred from one place to another.

Friction The resistance that one surface or object encounters when moving over another.

Gravitational potential energy The energy that must be used against gravitational forces to move a particle of mass.

Joules (J) The measurement of work done and energy transferred.

Kinetic energy This is the energy something has when moving.

Kinetic energy This is the energy something has when moving.

Momentum The tendency of the object to keep moving in the same direction

Power How quickly work is being done and therefore how quickly energy is being transferred.

Reaction time The time that goes by between a stimulus and the response to it.

Seat belt A safety device used in a car or plane to cause you to slow down over a longer period of time, thus reducing the force on the body in an accident.

Stopping distance Stopping distance is the distance it takes for a car to stop from a specific speed.

Thinking distance The thinking distance is the distance travelled in between the driver realising he needs to brake

Vector quantity An amount or measurement that is related to a direction. Velocity, acceleration, and weight are vector quantities

Watts (W) The measurement of power, it is equal to one joule per second.

Work The amount of energy transferred doing something.

Alpha particles Ionising radiation containing 2 neutrons and 2 protons (helium nucleus).

Atomic number The amount of protons that an element has.

Beta particles High-speed electrons that are emitted from an unstable nucleus

Chain reaction A reaction which causes many others one after the other.

Control rods Structures which absorb the neutrons, these are placed between the fuel rods in the core

Core Where the fuel and control rods are placed and the reaction is occurring.

Daughter nuclei The remaining nuclide left over from radioactive decay.

Decays When the nucleus of an atom breaks down causing it to emit radiation

Gamma rays High frequency electromagnetic waves emitted by some unstable nuclei and so travel at the speed of light

Ion An atom which has gained or lost electrons.

Ionising radiation Radiation that causes atoms to lose electrons and become ions

Isotopes A different atomic form of the same element with the same number of protons but a different number of neutrons.

Mass number The number of protons and neutrons in the nucleus of an atom.

Moderator Something that slows down a nuclear reaction by slowing/absorbing neutrons.

Nuclear fission A nuclear reaction in which a heavy nucleus splits spontaneously or on impact with another particle, with the release of energy

Nuclear fusion A nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy

Nuclear reactors This transforms the energy contained in the nuclei of uranium and plutonium atom, into thermal energy using nuclear fission

Nucleon number The number of protons and neutrons found in the nucleus of an atom. An alternative name for mass number.

Nucleons The particles found in the nucleus are called this.

Penetration distance How far ionising radiation can travel through a substance.

Proton number The number of protons that an element has.

Radioactive When a substance has an unstable nucleus, resulting in release or nuclear radiation.

Random Without a fixed time or pattern.

Sub-atomic particles The smaller particles that make up an atom.

Unstable An atom which has too many neutrons could be said to be this.

Activity How much radiation is produced.

Background count The amount of background radiation.

Background radiation Small amounts of radiation in the atmosphere

Becquerel (Bq) A unit of measurement, number of nuclear decays per second.

Cosmic rays The radiation emitted from space.

Count rate Number of clicks per second or minute of ionising radiation

Electrostatic repulsion When two of the same charges repel each other

Geiger-Müller (GM) tube Measures intensity of radiation.

Half-life The time taken for half the undecayed nuclei to decay.

Hazards Dangers to a person or object

High level waste (HLW) Sealed in glass canisters and concreted over until the radiation becomes low level.

Intermediate level waste (ILW) Contained in metal cylinders because they become radioactive.

Irradiated To expose to radiation. For example to when you expose food to gamma rays to kill microorganisms you are irradiating the food.

Low level waste (LLW) Not as radioactive, buried and compacted in special sites.

Mutation The changing of a structure, resulting in a variant

Peer-reviewed Reviewed by someone with knowledge on the subject

Radioactive Something that emits ionising radiation

Radioactive decay When an unstable radioactive nuclei decays and emits ionising radiation.

Radioactive waste Made up of radioactive daughter nuclei and radioactive isotopes formed when the materials in the core absorb neutrons

Radiotherapy The controlled use of high energy X-rays to treat many different types of cancer. In some cases, radiotherapy can also be used to treat non-cancerous tumours.

Radon A gas emitted produced by the natural decay of radioactive sources. E.g. Uranium.

Risk A situation involving exposure to danger

Sterilised To make something free from bacteria or other living microorganisms using Radiation

Tracer These are used for tracking substances such as: -Find leaks or blockages in underground pipes -Find the route of underground pipes -Track the dispersal of waste

Validated To check or prove the accuracy of something

P3 Core Questions

Topic 1

How is physics used to diagnose medical problems?

X-ray imaging, CAT scans, PET scans, Endoscopes and ultrasound scanning.

How is physics used to treat medical problems? Radiotherapy with gamma rays for cancer, lasers for skin and eyes, ultrasound for kidney stones and muscle problems.

Name one type of ionising radiation used in medicine.

Radiotherapy with gamma rays.

Name one type of non-ionising radiation used in medicine.

Endoscopes using visible light.

What is radiation? Any type of energy that spreads out from a source, particles or waves.

How is intensity affected by distance? Intensity decreases with distance (inverse square law applies here).

How is intensity affected by the medium? Different materials absorb different amounts of energy and so affect intensity differently.

Intensity = Power ÷ Area. What are the units? Intensity W/m2. Power W and area m2 If you were given the intensity and the power, how could you calculate the area?

Area = Power ÷ Intensity

What type of lens is a converging lens? A lens that is thicker in the middle to refract the light rays together and focus them at a point behind the lens. It will always have a positive focal length.

What type of lens is a diverging lens? A lens that is thinner in the middle to refract the light rays

away from each other and focus them at a point in front of the lens. It will always have a negative focal length.

How is the power of a convex lens related to its shape?

The thicker the lens, the more powerful it is.

How is the power of a lens related to its focal length?

The more powerful the lens, the shorter the focal length.

Power of a lens = 1÷ Focal length. What are the units?

Power of a lens is measured in dioptres (D). The focal length is measured in metres (m).

In the lens equation, what do f, u and v stand for and in which unit are they all measured?

F= focal length, u = object distance, v = image distance. All measured in metres (m).

What is a real image? An image that can be formed on a screen that is on the opposite side of the lens to the object. It is magnified and inverted with a positive focal length.

What is a virtual image? An image formed on the same side of the lens as the object. It is magnified and the right way up. It cannot be projected onto a screen and the focal length is always shown as negative.

Name the labelled parts of the eye:

How is light focused on the retina? Light enters the eye through the cornea where it is refracted. Light travels through the pupil and is further refracted by the lens to focus on the retina.

What is the job of the iris? To control the size of the pupil and therefore control the amount of light entering reaching the retina.

What is the job of the ciliary muscles? They contract and relax to change the shape of the lens, from thicker to thinner respectively, and so refract the light correctly to focus it on the retina, when looking at near and far objects respectively.

What is the near point? The point nearest the eye at which an object can be focused. 25cm for a normal adult.

What is the far point? The maximum distance a normal eye can see things. It is said to be at infinity.

What is short sight? Can see close objects but not able to clearly see objects at a distance. It is often caused because the eyeball is too long or the cornea is too curved.

What is long sight? Cannot see close up but can focus at a distance. This can be caused by old age because the lens becomes stiffer over time but can be because the eyeball is too short.

How can short sight be corrected with glasses? Use diverging lens in the glasses. How can long sight be corrected with glasses? Use converging lens in the glasses. Apart from spectacles, what other treatments are available for sight problems?

Contact lenses are lightweight and relatively inexpensive but they carry a risk of infection if not properly cleaned. Laser surgery is an expensive option and has the risk of complications but after no glasses or lenses need to be worn at all.

Draw a labelled diagram to show reflection from a mirror.

Draw a labelled diagram to show refraction of light as it leaves a glass block into air.

Draw a labelled diagram to show the path of light with an angle of incidence equal to the critical angle as it leaves a glass block into air.

Draw a labelled diagram to show the path of light with an angle of incidence greater than the critical angle as it travels through a glass block in air.

Explain how to calculate the critical angle using Snell’s law

When the critical angle is the angle of incidence, the light will be refracted along the edge of the block and so, the angle of refraction is 90 degrees. Sin 90 = 1. Sin c = the refractive index of the material the light is going into ÷ the refractive index of the material the light is coming from.

What are the two things that change in refraction?

Speed and direction.

How is density related to the speed of light? The greater the density of the material, the slower the light will travel and the more energy will be absorbed.

How is total internal reflection used in optical fibres?

Where are endoscopes used in diagnosis? Visual inspection of internal organs for example in colonoscopy.

Where are endoscopes used in treatment? Biopsies can be taken and eye hole surgery performed. Where is ultrasound used in diagnosis? Scanning during pregnancy and to locate kidney stones, cysts

etc in internal organs Where is ultrasound used in treatment? To break up kidney stones and in treating muscle problems.

Topic 2

What are X-rays? High energy electromagnetic waves. They are a type of ionising radiation. They have a high frequency and a short wavelength.

What is the process where electrons are boiled off a cathode (filament) called?

Thermionic emission.

Why is a voltage needed across the cathode (filament) in a simple electron gun?

To provide the ionisation energy to the electrons using the heating effect of current.

Why is a high voltage (potential difference) needed between the cathode (-) and the anode (+)?

To accelerate the electrons by repelling them away from the cathode and towards the anode.

Why is there a vacuum in an electron gun? So there are no particles to get in the way. Electrons are accelerated straight across and their kinetic energy is not wasted.

What name is given to the beam of electrons in an electron gun?

Cathode rays.

A bundle of fibres

is used. Light is

sent along some

of the fibres, at an

angle greater than

the critical angle

of glass, from the

light source and it

travels along the

fibres by total

internal reflection

as shown. The

reflected image

travels back to the

eye along other

fibres.

If the anode (+) is used as a metal target, what are produced?

X-rays

Why are X-rays produced when the anode (+) is used as a metal target?

The kinetic energy of the electrons is converted into X-rays on collision.

What is an electric current? The rate of flow of negative charge.

Why are cathode rays equivalent to an electric current?

Cathode rays are a beam of electrons, electrons are negatively charged particles. You have a number of negative charges flowing per second.

In the equation I = N x q state what each letter stands for and the units each is measured in.

I = Current in amps (A) N = Number of particles per second q = Charge on each particle in coulombs (C).

What unit is kinetic energy measured in? Joules (J)

Which two equations for kinetic energy link together? KE = ½ mv2 and KE = eV so that ½ mv2 = eV

In the electron gun question ½ mv2 = eV state each letter stands for and the units each is measured in.

m = mass in kilograms (kg) v = velocity in meters per second (m/s) e = charge on an electron in coulombs (C) 1.6x10-19 C V = Accelerating potential difference in volts (V)

What does the intensity of radiation, like X-rays, depend on?

Distance from the source and the medium (material) travelled through.

How does distance from the source affect intensity? The inverse square law explains how if the distance from the source is doubled, the intensity is ¼. This is because the area covered is 4 times as big.

Why does the medium travelled through affect intensity?

Some materials absorb more than others, generally the more dense a material, the more it absorbs and the less radiation gets through so it is less intense.

How does the thickness of a material affect intensity? The thicker the material the less the intensity because more radiation will be absorbed by thicker materials.

How are X-rays used in CAT scans? To produce 2D slices through the body by rotating X-rays around the area being investigated.

How are X-rays used in fluoroscopes? To create moving images of the inside of the body by placing the patient between an x-ray source and a fluorescent screen.

What are the risks of using X-rays? X-rays are an ionising form of radiation and so they can cause molecules in living cells to be ionised. This may lead to tissue damage of cancer.

What are the benefits of using X-rays? Allows proper diagnosis to plan treatment better. It is non-invasive and so is quick to perform and does not require surgery.

What do ECG’s measure? Electrocardiograms measure the action potentials that pass through the atria and the ventricles of the heart.

What does the action potential cause a muscle cell to do?

Contract.

What happens to a muscle cell after an action potential has passed?

Relaxes.

P is where the atria contract because of an action potential. QRS section is where the ventricles contract because they have an action potential through them and the atria are relaxing because their action potential has passed. T is where the ventricles relax because the action potential through them has passed. The time for 1 heart beat can be found by measuring from R to the next spike on the x-axis.

In the equation: frequency = 1/time period state the units for each part.

Frequency in hertz (Hz), Time period in seconds (s). But it is often useful to give answers in beats per minute and so the frequency has to be multiplied by 60.

What is a pacemaker used for? It is a device that is used to regulate the heart beat.

Describe

this ECG

trace.

How does a pacemaker work? It uses small electric impulses to stimulate the heart to beat.

What is a pulse oximeter? It is a device that can be fitted to the finger that allows the % of oxygen in the blood to be measured and the heart rate too.

How does a pulse oximeter work? 2 types of light (red and infra red) are sent through the finger and detected on the other side. The amount of light absorbed is measured and this depends on the colour of the blood. The colour of the blood depends on the oxygen content.

Topic 3

Why might a radioactive technique like PET scanning or CAT scanning not be used?

If a women is pregnant, if the side effects are greater than the benefits for the long-term health of the patient or the cost cannot be justified.

What are the properties of alpha radiation? Alpha particles are identical to a helium nucleus as they are made up from 2 protons and 2 neutrons. They have a charge of +2 and a relative mass of 4. They are highly ionising but not very penetrating. They are affected by electric and magnetic fields.

What are the properties of beta radiation? Beta particles are high energy electrons that are released from the nucleus of the atom. They have a charge of +1 and a relative mass of 1/2000. They are ionising and fairly penetrating. They are affected by electric and magnetic fields.

What are the properties of gamma radiation? Gamma is a high frequency electromagnetic wave. These waves have no charge or mass. They are weakly ionising but very penetrating. They are not affected by electric and magnetic fields.

What are the properties of positron radiation? Positron particles are the anti-particle to the electron. They are released from the nucleus of the atom and have a charge of +1, They have a relative mass of 1/2000. They are ionising and fairly penetrating. They are affected by electric and magnetic fields.

What are the properties of neutron radiation? Neutrons can be released from the nucleus of some radioactive isotopes. They have no charge. They have a relative mass of 1. They are ionising and penetrating. They are not affected by electric and magnetic fields. They are called thermal neutrons.

What is the relationship between the number of protons and the number of electrons in an atom?

They are equal and the atom has no overall charge.

What happens in beta minus decay in terms of particles?

A neutron becomes a proton + an electron. This causes the atomic number (proton number) to increase by 1 while the mass number (nucleon number) stays the same.

What happens in beta plus decay in terms of particles?

A proton becomes a neutron + a positron. This causes the atomic number (proton number) to decrease by 1 while the mass number (nucleon number) stays the same.

What is the effect on the mass number (nucleon number) in alpha decay?

Decreases by 4.

What is the effect on the mass number (nucleon number) in gamma decay?

Nothing.

What is the effect on the mass number (nucleon number) in neutron decay?

Decreases by 1.

What is the effect on the atomic number (proton number) in alpha decay?

Decreases by 2.

What is the effect on the atomic number (proton number) in gamma decay?

Nothing.

What is the effect on the atomic number (proton number) in neutron decay?

Nothing.

In a nuclear equation what do you need to balance? The mass number (nucleon number) before with the total mass numbers (nucleon numbers) of the new isotope and released particles after and the atomic number (proton number) before with the total atomic numbers (proton numbers) of the new isotope and released particles after.

What shape graph do you get when you plot stable nuclei on a N-Z graph (Number of neutron against number of protons)?

A curve called the curve of stability.

With reference to the curve of stability, where would you find a radio-isotope that decays by emitting alpha radiation?

Above 82 protons and not on the curve.

With reference to the curve of stability, where would you find a radio-isotope that decays by emitting beta + radiation?

Below 82 protons and below the curve. This isotope will have too few neutrons (or too many protons) to be stable.

With reference to the curve of stability, where would you find a radio-isotope that decays by emitting beta - radiation?

Below 82 protons and above the curve. This isotope will have too many neutrons (or too few protons) to be stable.

What are protons and neutrons made up of? Quarks. A proton is two up quarks and a down quark (uud). A neutron is two down quarks and an up quark (ddu).

Using quarks show the mass of a proton is 1. Up quarks have a relative mass of 1/3. Down quarks have a relative mass of 1/3. A proton is two up quarks and a down quark (uud). 1/3 + 1/3 + 1/3 = 1

Using quarks show the mass of a neutron is 1. Up quarks have a relative mass of 1/3. Down quarks have a relative mass of 1/3. A neutron is two down quarks and an up quark (ddu). 1/3 + 1/3 + 1/3 = 1

Using quarks show the charge of a proton is +1. Up quarks have a charge of +2/3. Down quarks have a charge of -1/3. A proton is two up quarks and a down quark (uud). 2/3 + 2/3 -1/3 = +1

Using quarks show that a neutron has no charge. Up quarks have a charge of +2/3. Down quarks have a charge of -1/3. A neutron is two down quarks and an up quark (ddu). 2/3 – 1/3 – 1/3 = 0

What happens in beta minus decay in terms of quarks?

A down quark becomes an up quark. This means that a neutron becomes a proton + an electron. This causes the atomic number (proton number) to increase by 1 while the mass number (nucleon number) stays the same.

What happens in beta plus decay in terms of quarks? An up quark becomes a down quark. A proton becomes a neutron + a positron. This causes the atomic number (proton number) to decrease by 1 while the mass number (nucleon number) stays the same.

When is gamma radiation emitted? When a radioisotope undergoes decay by alpha or beta (+ or -) emission, the nuclear rearrangement usually results in the excess energy being released as gamma radiation.

What are the dangers of ionising radiation? In low doses, can cause cancer as there may be damage to DNA. In high doses, can cause skin burns, radiation sickness and even death.

What precautions are taken to ensure the safety of patients and staff involving in using radiation medically?

Radiation is monitored, dose and exposure time are limited. People are also protected with screening and protective clothing.

How are radiotherapy and brachytherapy similar? Both use radioactive isotopes to destroy cancer cells by damaging the DNA of the cancerous cells.

How are radiotherapy and brachytherapy different? Radiotherapy is an external treatment. High energy gamma radiation or X-rays are used over a period of time to target cancerous cells using a multiple beam approach to limit the damage to healthy cells by reducing the intensity of the radiation through them while maintaining the higher intensity needed at the site. Brachytherapy is an internal treatment which is only used in specialised cases. It has the advantage of treating the cancerous cells more directly but requires surgery.

What is meant by palliative care? The use of radiotherapy to alleviate the severity of the symptoms and so reduce pain or extend life expectancy by reducing the progress of the disease but it does not offer a cure. It is used to improve the quality of life for the terminally ill patient.

How are radioactive sources used in medical tracers? It is possible to trace the blood flow through an organ by being injected into the blood stream and monitored using a gamma camera. Gamma sources are used so that the radiation can escape from the body and be traced. The dose is kept as small as possible to minimise the effect of the ionising radiation. The half-life of the source needs to be short enough to make sure the patient does not remain radioactive but long enough to ensure the full investigation can be performed. Tracers are often tied to a compound that is attracted to cancerous cells like glucose.

What is a PET scan? Positron emission tomography can be used to detect small changes in cells and identify rapidly growing cells, such as cancer cells. Fluorine-18 is used because it decays by positron emission. When the emitted positrons collide with electrons the two particles are annihilated releasing two gamma rays in opposite directions. A ring of gamma detectors detect the gamma rays and can calculate the point they were emitted from in the body. The radioisotope needs to have a short half-life, F-18 has a half-life of 110 minutes. This is short enough to make sure the patient does not remain radioactive for long after the PET scan but is long enough to ensure the full investigation can be performed. PET images and CT images can be combined to provide a very useful diagnostic tool.

Why do radioactive sources used in PET scanners need to be produced near to the scanner?

The half-life of the source needs to be short so that the patient is not still radioactive after the scan and so it needs to be produced nearby and relatively near to the time of the scan so that it remains radioactive for the duration of the scan. F-18 has a half-life of 110 minutes.

Topic 4

Telescopes enabled astronomers to develop better explanations about our solar system and seismometers allow geologists to

Particle accelerators can be used to accelerate charged particles to very high energies and smash them together in an effort to learn about the fundamental particles, like quarks, that make up our

predict earthquake locations. How do particle accelerators allow physicists to develop better explanations about the physical world?

universe. Physicists can study the nature of matter, energy, space and time using particle accelerators like the LHC (Large Hadron Collider).

Why is there collaboration between countries in the area of particle physics?

To answer the sorts of questions they are investigating at CERN requires the sharing of expertise, skills and knowledge. Scientists and engineers from over 100 countries and in hundreds of universities are involved. In addition to this, the cost of particle accelerators like the LHC is huge, the initial cost was over £3 billion, this collaboration also shares the costs.

When an object moves in a circle at a constant speed, is the velocity constant? Explain!

No. The direction is changing and velocity is a vector quantity, the direction is important.

When an object moves in a circle at a constant speed, why is it accelerating?

There is a change of velocity over time, therefore the object is accelerating.

When an object moves in a circle at a constant speed, what causes the acceleration? (what must there be for an object to move in a circle?)

A resultant force.

What is this resultant force called? Centripetal force.

What direction is the centripetal force in? Towards the centre of the circle.

How do cyclotrons cause charged particles to move in a circular or spiral path?

A magnetic field (in the dees) forces the particles to move in a circle. The particles are accelerated by an electric field (in the gap between the dees) and the increased speed causes them to move outward from the centre in a spiral path.

What is the relationship between the number of times a charged particle spirals before leaving the cyclotron and the amount of energy they have?

The more times the particle spirals, the greater the amount of kinetic energy because they increases in speed with each spiral.

If certain stable isotopes are bombarded with protons from the cyclotron what is made?

Radioactive isotopes that can be used in medicine. For example the radioisotope fluorine-18 is produced from oxygen-18 in this way.

What is the nuclear equation for the bombardment of oxygen-18 with a high energy proton?

What is the stated in the law of conservation of energy?

That the TOTAL amount of energy before and after a transformation is the same.

What is the stated in the law of conservation of momentum?

The total momentum before a collision is equal to the total momentum after the collision.

Why is direction important in momentum problems?

Momentum is a vector quantity, it has both size and direction.

What are the units for momentum? kgm/s (kilogram metres per second)

What is an inelastic collision? A collision where some of the kinetic energy is wasted as thermal energy and sound.

What is an elastic collision? A perfect collision where all the kinetic energy before is transferred to the kinetic energy after.

What type of collision conserves kinetic energy?

Only elastic collisions.

What type of collision conserves momentum?

Both elastic and inelastic collisions.

Which equation is used to calculate kinetic energy? State all the units.

KE= ½ m v2 Units are: KE (J) joules, m (kg) kilograms and v (m/s) metres per second

Which equation is used to calculate momentum?

Momentum = mass x velocity

What is produced when fluorine-18 decays? A positron and the fluorine-18 becomes the stable isotope oxygen-18.

What is the nuclear equation for the radioactive decay of fluorine-18?

What happens when a positron meets an electron?

The particles are annihilated causing 2 gamma rays to be emitted in opposite directions.

Where is the annihilation of positrons and electrons used?

In PET scanners (positron emission tomography) for the diagnosis and monitoring of cancer.

What is a PET scan? Positron emission tomography can be used to detect small changes in cells and identify rapidly growing cells, such as cancer cells. Fluorine-18 is used because it decays by positron emission. When the emitted positrons collide with electrons the two particles are annihilated releasing two gamma rays in opposite directions. A ring of gamma detectors detect the gamma rays and can calculate the point they were emitted from in the body. The radioisotope needs to have a short half-life, F-18 has a half-life of 110 minutes. This is short enough to make sure the patient does not remain radioactive for long after the PET scan but is long enough to ensure the full investigation can be performed. PET images and CT images can be combined to provide a very useful diagnostic tool.

Why do radioactive sources used in PET scanners need to be produced near to the scanner?

The half-life of the source needs to be short so that the patient is not still radioactive after the scan and so it needs to be produced nearby and relatively near to the time of the scan so that it remains radioactive for the duration of the scan. F-18 has a half-life of 110 minutes.

How is the annihilation of an electron and a positron an example of the conservation of momentum?

The electron and the positron collide head on, they have the same mass and are both moving with the same speed but in opposite directions. The overall momentum is therefore zero. The gamma rays are emitted in opposite directions with equal and opposite momentum, so the overall momentum is zero too.

How is the annihilation of an electron and a positron an example of the conservation of charge?

The two particles have opposite charges. Overall charge is therefore zero before the collision. After the collision gamma rays are produced that have no charge. After the collision the charge is also zero.

What does Einstein’s equation E=mc2 show? Einstein’s equation E=mc2 shows that mass can be converted into energy and energy into mass.

How is the annihilation of an electron and a positron an example of the conservation of mass energy (E from the Einstein equation)?

When the particles are annihilated, the masses of both particles are converted into energy. The 2 gamma rays that are produced have energy equal to the mass of the 2 original particles. Mass energy (E) is conserved.

Use a nuclear equation to show the annihilation of a positron and electron.

0

1 e +

0

-1 e 0

0 γ 2

Use the kinetic energy equation to show the conservation of mass energy in an annihilation of a positron and electron.

Topic 5

Describe the movement of the particles in a solid.

The particles are just vibrating in their fixed positions, close together in nice neat rows.

Describe the movement of the particles in a liquid.

The particles are moving past one another, close together in a random pattern.

Describe the movement of the particles in a gas.

The particles are moving very quickly in random directions and they are far apart form each other.

How is the pressure of a gas related to the motion of the particles?

As the particles get more kinetic energy they move more. As the particles get faster they hit the sides of the container more often and harder. This causes an increase in pressure.

What is absolute zero? The temperature at which particles have no kinetic energy and so no pressure. It is the temperature of 0K or -273C.

Describe the movement of the particles at absolute zero.

They are close together in neat rows and they are stationary. They do not move at all.

How do you convert a temperature in C into K?

+273

How do you convert a temperature in K into C?

-273

What is the relationship between kinetic energy of the particles in a gas and its temperature in Kelvin?

As a gas is heated up and temperature increases the particles gain more energy. With more kinetic energy the particles move faster. Temperature (in K) and kinetic energy are directly proportional.

What is the relationship between volume of a gas and its temperature in Kelvin, for a fixed mass and pressure of gas?

As a gas is heated up and temperature increases the particles will need more space to maintain the same pressure. This is because they have more energy and so move faster and if the volume did not increase they would hit the sides of the container more often. Temperature and volume are directly proportional.

What is the relationship between volume of a gas and its pressure, for a fixed mass and temperature of gas?

As the volume of a gas decreases, the particles would hit the walls more often and so the pressure would increase. Volume and pressure ate inversely proportional to each other.

In the ideal gas equation what does the P stand for and what units can it be measured in?

Pressure. Pascals Pa or N/m2

Before the collision:

E = 2 x 9.11 x 10-31 Kg x (3 x 108 m/s)2

E = 1.64 x 10-13 J

After the collision:

2 gamma rays are produced so each has an energy of :

E = 1.64 x 10-13 J / 2 = 8.2 x 10-14 J

Because the total energy is conserved

In the ideal gas equation what does the T stand for and what units can it be measured in?

Temperature. Kelvin K and only K!!

In the ideal gas equation what does the V stand for and what units can it be measured in?

Volume. m3 or cm3 as long as the same throughout the calculation.

In the ideal gas equation what are the numbers 1 and 2 for?

1 = before and 2 = after.

Why are the gases that are used in medicine stored in special bottles?

To save storage space. By compressing the gas more gas can be squashed into a smaller volume. This is done by increasing the pressure above atmospheric pressure of 100 000 Pa.

P3 Keywords and Definitions

Topic 1

Angle of incidence The angle between the normal and the ray when it hits a surface

Angle of reflection The angle between the normal and the reflected ray when it leaves the surface

Ciliary muscles Muscles that help to change the shape of the eye lens

Converge Bring closer together

Converging lens A lens that brings light rays together (convex lens)

Cornea The curved layer over the front of the eye

Critical angle The angle of incidence in a denser medium that gives an angle of refraction equal to 90

Dioptre (D) A unit for the optical power of a lens

Diverege Spread out further way

Diverging lens A lens that spread light out (concave lens)

Endoscope An instrument used by doctors to look inside the body

Far point The furthest point the eye can see clearly

Focal length The distance between the centre of the lens and principal focus

Intensity The power of radiation per unit area

Inverse square law A relationship between quantities where doubling one quantity reduces the related quantity by a factor of 4

Iris The coloured part of the eye that controls the amount of light entering the eye

Laser correction Using a laser to permanently reshape the curvature of the cornea so that the focal length of the eye is changed

Law of reflection The angle of reflection equals the angle of incidence for a ray at a surface

Lens Further converges light (which have been refracted by the cornea) to focus them on the retina

Lens equation An equation that relates image distance v, object distance u and the focal length f: 1/u + 1/v = 1/f

Long sight Eyesight problem when a person can see distant objects but cannot focus properly on near objects. Caused by light rays being focused to a point behind the retina. Can be corrected using converging lenses or laser surgery

Near point The closest distance the eye can focus an object usually about 25cm

Optical fibres Thin and flexible tubes of transparent material for transmitting light from one end to another

Optical power A quantity found using the equation 1/f where f = focal length in metres. It is measured in dioptres (D)

Principal focus (or focal point)

The point at which rays of light parallel to the principal axis of a converging lens converge, or the point from which rays parallel to the principal axis of a diverging lens appear to come

Pupil The central hole produced by the iris

Radiation Any form of energy that originates from a source, including waves and particles

Real image An image that can be projected onto a screen

Refract The change of direction of a wave due to the change in speed at an interface between 2 media

Refractive index The ratio of the speed of light in a vacuum to the speed of light in a particular material

Retina Light sensitive part of the eye on which images are formed

Short sight Eyesight problem when a person can see near objects but cannot focus properly on distant objects. Caused by light rays being focused to a point in front of the retina. Can be corrected using diverging lenses or laser surgery

Snell’s law An equation that relates the angle of incidence i in a vacuum (or air), the angle of refraction r in a medium and the refractive index n of the medium; sin i / sin r = n

Total internal reflection

Reflection of light in a denser medium when the angle of incidence is greater than the critical angle

Ultrasound High-frequency sound waves (above 20 000Hz) that humans cannot hear

Virtual image An image that cannot be projected onto a screen

Topic 2

Action potential Change in voltage across a neurone or the membrane of a cardiac muscle cell when an

electrical impulse travels along it.

Anode Positive electrode.

CAT scan Computerised Tomography. An x-ray picture that shows a slice through the body.

Cathode Negative electrode.

Diagnosis Identifying a medical condition by its signs and symptoms or from a medical imaging scan.

ECG Electrocardiogram. A graph showing the change in potential difference produced by the heart, used to monitor heart action.

Electron gun A heated cathode that emits electrons, and the apparatus that focuses the beam of electrons.

Evacuated tube A tube from which the air has been removed so that there is a vacuum.

Filament A thin wire. In thermionic emission a heated filament emits electrons and forms the cathode when current is passed through an evacuated tube.

Fluoroscope A device that uses X-rays and a fluorescent screen to obtain moving pictures of the inside of the body.

Frequency The number of cycles of a wave per second (or complete heart beats in this topic), measured in hertz (Hz)

Intensity The strength of a wave (X-rays in this topic) defined as power/area.

Inverse square law Any law of physics in which the value of a physical quantity is inversely proportional to the square of the distance from the source of that physical quantity. Applies to the strength of X-ray radiation in this topic.

Ionising radiation Radiation that can cause charged particles to be formed by knocking outer electrons out of the atom, or giving them enough energy to break free from the atom. Causes tissue damage and may cause mutations.

Pacemaker A device which helps the heart to beat properly by detecting the action potentials and applying electrical signals to regulate the heart action.

Potential difference Another word for voltage. It is the difference in the energy carried by electrons before and after they have flowed through a component.

Pulse oximetry Using a pulse oximeter to measure the pulse rate and amount of oxygen in the blood.

Thermionic emission The process of emitting an electron fro the surface of a heated metal, usually a hot filament.

X-Ray Electromagnetic wave with a high frequency and high energy. X-rays are ionising radiation.

Topic 3

Alpha particle Particle made of 2 protons and 2 neutrons, emitted as ionising radiation from some radioactive sources.

Annihilation Destruction caused by interaction of a particle with its anti-particle.

Antimatter Matter made up of anti-particles, such as positrons.

Beta minus decay Emission of a high energy electron from an unstable nucleus when a down quark becomes an up quark.

Beta plus decay Emission of a positron from an unstable nucleus when an up quark becomes a down quark.

Cyclotron A particle accelerator used to produce radioactive isotopes used in PET scanners.

Down quark A fundamental particle with a charge of -1/3.

Electron A negatively charged particle found in atoms.

Fundamental particle A particle that cannot be broken down into smaller units. At present quarks, electrons and positrons are all thought to be examples of fundamental particles.

Gamma camera A special camera used to produce a 3 dimensional image of the body using gamma rays emitted from inside the body.

Gamma radiation Ionising radiation in the form of pulses of electromagnetic radiation with very short wavelengths.

Half-life The time taken for half of a radioactive element to decay to its non- radioactive product.

Ionising radiation Radiation that can cause charged particles to be formed by knocking outer electrons out of the atom, making the atom into an ion. Causes tissue damage and may cause mutations.

Isotopes Atoms with the same number of protons but different numbers of neutrons.

Neutrino A particle with no charge and a very small mass emitted during beta-plus decay of unstable nuclei. (PTO)

Neutron Small particle which does not have a charge, found in the nucleus of an atom. It is made up from 1 up quark and 2 down quarks.

Nuclear equation Equation representing a nuclear reaction, i.e. a change in the nucleus due to radioactive decay, balancing the atomic number and mass number.

Nucleons Protons and neutrons (both found in the nucleus of an atom)

Palliative care A medical intervention that does not cure a condition but may reduce pain or other symptoms and may extend life expectancy.

Particle accelerator A machine used to accelerate charged particles to very high speeds.

PET scanner A special scanner used to produce images of the metabolic functions of the body.

Positron The anti-particle of an electron; a particle with a similar mass to an electron but with an opposite charge (it has a positive charge).

Proton Small positive particle found in the nucleus of an atom. It is made up from 2 up quarks and 1 down quark.

Quark A fundamental particle within particles such as protons and neutrons.

Stability curve A curve on a N-Z (number of neutrons against number of protons) graph showing the positions of all stable nuclei.

Strong nuclear force An attractive force between all neutrons and protons.

Up quark A fundamental particle with a charge of +2/3.

Topic 4

Annihilation Destruction caused by interaction of a particle with its anti-particle.

Centripetal force The resultant force acting at right angles to the velocity of an object that gives rise to circular motion.

Cyclotron A particle accelerator used to produce radioactive isotopes used in PET scanners.

Elastic collision A collision in which momentum and energy are both conserved.

Inelastic collision A collision in which momentum is conserved but kinetic energy is not because some of the energy is transformed into other forms such as thermal energy and sound.

Mass-Energy equation Einstein’s equation E=mc2 which links mass and energy.

Momentum A quantity calculated by multiplying the mass of an object by its velocity. It is a vector quantity as it has both size and direction.

Particle accelerator A machine used to accelerate charged particles to very high speeds.

PET scanner A special scanner used to produce images of the metabolic functions of the body.

Positron The anti-particle of an electron; a particle with a similar mass to an electron but with an opposite charge (it has a positive charge).

Radiopharmaceutical A substance produced by tagging radioactive isotopes to natural chemicals such as glucose and water.

Topic 5

Absolute zero A temperature equivalent to -273.15C or 0K; all atoms or molecules stop moving

at this temperature

Atmosphere (atm) A unit of pressure

Atmospheric pressure The pressure exerted by the atmosphere of the Earth; at sea level the atmospheric pressure is 100kPa or 1 atm

Boyles law The pressure exerted by a fixed mass of gas, kept at constant temperature, is inversely proportional to its volume

Charles law The volume occupied by a fixed mass of gas, kept at a constant pressure, is directly proportional to its temperature on the Kelvin scale

Gas equation PV/T = constant

Heat A measure of the thermal energy in an object. It is measured in joules (J)

Ideal gas equation PV=nRT describes the relationship between pressure, volume, temperature and number of moles of gases

Kelvin The standard unit of temperature

Kelvin temperature scale A temperature scale that measures temperatures relative to absolute zero

Kinetic energy The energy that a particle has due to its movement. It can be calculated in joules (J) using the equation KE= ½mv2

Kinetic theory The theory that explains the different states of matter in terms of the movement of particles

Pascals (Pa) A unit of pressure. 1Pa = 1N/m2

Pressure The force on a certain area. It is measured in the standard unit of Pascals (Pa)

Pressure law The pressure exerted by a fixed mass of gas, kept at a constant volume, is directly proportional to its temperature on the Kelvin scale

Temperature A measure of how hot an object is. It can be measured in C for convenience or in the standard unit of Kelvin (K)