HomeworkBlue Book pg 153-154

#1-25 on a separate sheet of paper!Collected and graded tomorrow!

Do Now:Draw a wave and label any part of the wave

you know.

AIM:What is a wave and how do we measure and

describe them?

Simple Harmonic Oscillators

• An object in simple harmonic motion experiences a restoring force that continuously pulls the object back towards its equilibrium positon.

• The oscillator vibrates about an equilibrium position (or mean position) between two extreme positions of maximum displacement in a periodic manner– Periodic means regular (same every time) and repeating

Mass on a springpendulum

Which of the following waves is

Periodic?A

B

Parameters and

parts of

waves

Vocabulary• Period (T):

– The time for one oscillation– Measured in Seconds– Period = Time/number of oscillations

• Frequency (f)– The number of oscillations in one second– Measured in Hertz; Hz (1/s or s-1)– Frequency = Number of oscillations/time

• Mathematical Relationship between Period and Frequency– Period and frequency are inversely related

1 1

1

TfT

ff

T

T

f

Examples1. A mass on a spring completes 10 oscillations in 30

seconds.a. What is the period of oscillation?b. What is the frequency of oscillation?

2. A pendulum completes 5 swings in a minutea. What is the frequency of oscillation?b. What is the period of oscillation?

3 seconds

0.33 Hertz

0.083 Hertz

12 seconds

• Waves are repetitive disturbances that transfer ENERGY without transferring MATTER – energy transferred without matter being transferred

• Mechanical Waves require a medium to travel through.• Mediums include; water, air, anything solid, liquid, or gas• SOUND is a mechanical wave • "the wave"

• Electromagnetic Waves do not require a medium to travel through. They can travel through a vacuum (empty space)

• Empty space exists outside of Earth’s atmosphere• LIGHT, Xrays, Radio Waves… are all examples of electromagnetic

waves• electromagnetic waves

Waves

Write out the full sentences and fill in the blank

1. A(n) ____________ wave can travel through a vacuum

2. ___________ is the number of waves that pass by per time.

3. A _________ is a substance a wave can travel through.

4. The amount of time it takes for one complete cycle of a wave is called the _____________.

5. A(n) __________ wave requires a medium to travel through.

Write out the full sentences and fill in the blank

1. A(n) ____________ wave can travel through a vacuum

2. ___________ is the number of waves that pass by per time.

3. The amount of time it takes for one complete cycle of a wave is called the _____________.

4. A(n) __________ wave requires a medium to travel through.

5. A _________ is a substance a wave can travel through.

Two Classes of WavesTransverse WavesThe particles vibrate in

a direction that is perpendicular to the waves propagation (direction of travel)

Longitudinal WavesThe particles vibrate in

a direction that is parallel to the waves propagation

Wave PulseOne single Vibration or disturbance

• Transverse Pulse • Longitudinal Pulse

One Crest Or

One Trough

One rarefaction Or

One compression

Parts of a WaveCrest: the top-most part of a wave

Trough: the bottom-most part of a wave

Amplitude: the distance from the equilibrium line to the crest or to the trough (measure in meters)

Wavelength (λ): the distance between two similar points on a

wave (measured in meters)

This is a ________________ wave which means that the particles vibrate ____________ to the direction the wave is moving.

On the wave above, label - One crest- One trough- One wavelength- One amplitude

This is a __________________ wave which means that the particles vibrate ____________ to the direction the wave is moving.

On the above wave, label- The compression- The rarefaction- One wavelength

Sound Waves vs. Light WavesSound Waves

• Mechanical Wave• Longitudinal wave• Amplitude tells you about

volume• Frequency tells you about pitch• The speed of sound in air is

about 330m/s• Sound travels faster in most

solids than it does in air

Light Waves

• Electromagnetic wave• Transverse wave• Amplitude tells you about

intensity• Frequency tells you about type

of wave/color• The speed of light in air is

3x108m/s• Light slows down in solids

Phase• The relative position between…

– Two different points on the same wave• Phase is measured in degrees and follows the

conventions of a sine curve.

Reference Point

0o

90o

One-quarter wavelength

180o

Half wavelength

270o

three-quarter wavelength

360o

One full wavelength

PhaseIN PHASE (360o)

– means the waves are in the exact same positons (carbon copies of each other)

180o out of phase• Means they are opposite each

other (1/2 a wave behind)

The relative position between two separate waves

standing wave• A wave that appears to be “standing still” and not moving either

left or right.- Particles vibrate up and down

• In order to create a standing wave, you need- Two waves, moving in opposite directions, with the same

amplitude and frequency

Nodes: points that don’t moveAntinodes: points that move the most

Standing Wave DiagramsFundamental Frequency (1st Harmonic)

λ=2L

2nd Harmonicλ=L

3rd Harmonic1.5λ=Lλ=2/3L

4th Harmonicλ=1/2L

Measuring Parameters of a Wave

• Goal: we are going to use a standing wave to measure and investigate the affect of the amplitude, frequency, period, and wavelength on the speed of a transverse wave.

• Prediction: Which of the four parameters do you think can be used to determine the speed of the wave and why.

• Background: in a paragraph, please define all bolded words above.

• Diagram: Draw a diagram of a transverse wave and label all the parts of the wave.

• Materials– Slinky, stopwatch, meter stick

Procedure• Using a slinky, we will create a standing wave between

two people standing 4 meters apart.• Once person will establish a frequency that will produce a

standing wave vibrating at its fundamental frequency with an amplitude of 0.5 meters

• Once the wave is established, the timers will time how long it takes for20 oscillations. Record the values in the table

• This will be repeated for an amplitude of 1m.• The frequency will then be changed to produce a standing

wave in the 2nd harmonic and steps 3-4 will be repeated.• Create a wave in the 3rd harmonic and repeat steps 3-4• Create a wave in the 4th harmonic and repeat steps 3-4

• Data

Amplitude of 0.5m Amplitude of 1.0m

wave-length

(m)

Time for 20

(s)

Period(s)

Frequency (Hz)

Speed (m/s)

wave-length

(m)

Time for 20

(s)

Period (s)

Frequency (Hz)

Speed (m/s)

• Analysis– Show a sample calculation for each of the following

• Period of the wave• Frequency of the wave• Speed of the wave.

– What formula did you come up with to calculate this? (hint: use the units!)

• Percent difference between velocities.– Do they appear different?

• Conclusion– Restate goal– What is the formula for the speed of the wave?– What parameters affect the speed, which don’t?

• If the frequency was changed, did the speed or the wavelength change?

– How could you change the speed of this wave?– Sources of error/one future experiment

Wave Propagationand ECHOs

Wave Propagation

When given distance 1. A wave moving at 4m/s travels 20m through the air. How long does it take?

5 seconds

2. How long does it take light to travel from the Earth to the moon?

1.28 seconds

𝒗=𝒅𝒕

Wave PropagationWhen given wavelength or

frequency λ3. Red light has a frequency of 4x1014 Hz. What is its

wavelength?7.5x10-7 m

4. A light wave has a wavelength of 480nm, what color is it?BLUE

Reflection of sound• The bouncing of a wave off of a surface.

• ECHOs

If the speed of sound in water is 1500m/s and the signal takes 0.8 seconds to come back to the boat, HOW DEEP IS THE WATER?

600m

Echos A person in the grand canyon (at STP) screams

and hears the sound come back to her 1.2 seconds later. How far away is the other face of the canyon? 199m

HOMEWORKCHECKED TOMORROW

Pg 153-155#26-47

HomeworkCastle Learning Assignment due FRIDAY!

Do Now:Find your partner and create your answer sheet to hand in for numbers 26-47 in the blue book

AIM:What is Reflection?

• You are standing on a dock and observe 15 waves pass you in 1 minute.– What is the frequency of the waves?– What is the period of the wave?

• What is the difference between a mechanical and electromagnetic wave?

• What is the difference between a transverse and longitudinal wave?

Recall…

0.25 Hz4 seconds

Mechanical waves need a medium to travel through, electromagnetic waves can

travel through a vacuum

A transverse wave has particles vibrating perpendicular to the direction of propagation, longitudinal waves have particles that vibrate

parallel to the direction of propagation.

• ALL electromagnetic waves travel at the speed of light!– c is the symbol for the constant “speed of light”– c is always equal to 3x108 m/s when electromagnetic

waves are traveling through a vacuum.• This speed can be decreased by sending light through a

different medium• Nothing can ever travel faster than the speed of light.• Visible light is the same type of wave as a radio wave, an Xray,

or a microwave. Its just a different size!• electromagnetic spectrum

The Electromagnetic Spectrum

The Electromagnetic Spectrum

VERY small wavelengths

VERY high frequencies

VERY high wavelengths

VERY low frequencies

Visible Spectrum. Each color is within these FREQUENCY ranges. Remember, higher frequency, lower wavelength

The Electromagnetic Spectrum

Nanometers Kilometers

Megahertz

meters

Gigahertz

The Electromagnetic Spectrum

• A wave has a frequency of 5.1x1014 Hz. – What color is it?– What is the order of magnitude of its wavelength?

• A wave has a wavelength of 10nm.– What 2 types of electromagnetic radiation could it

be?– What would be the order of magnitude of its

frequency?

yellow

10-7 m

X-rays or ultraviolet

1017 Hz or 1018 Hz

Calculating the speed of a wave1. A 5m long wave passes the end of a dock once

every 10 seconds.a. What is the period of the wave?b. What is the speed of the wave?

2. A light wave has a frequency of 6MHza. What is the frequency in Hertz?b. What is the speed of the wave?c. What is the wavelength of the light?d. What type of light wave is this?

10 seconds

0.5m/s

6x106 Hz

3x108 m/s

50m

Radio Waves

Wave Behavior

s

3 Options• When a wave hits a

boundary, it does a combination of 3 things– Reflection

• Bounces off the boundary

– Absorption • Gets absorbed and turned

into heat

– Transmission• Goes through the

boundary

The transm

ission of the lights

on the inside of the building

The reflection of the lights coming off the car on the outside of the building

When waves meet a

boundary1.2.3.

Two types of wave sourcesPoint Source

• One point that oscillates– Like a child bobbing in the

pool.– Produce circular waves

Plane Source• An extended (rectangular)

source that oscillates.– Produce plane waves

Diffraction• Diffraction is the bending of

a wave around a barrier– Consider a door cracked

open, what shape does the light make?

• If it didn’t bend, it would be a straight column

• As you can see the light ‘fans out’ after it passes through the barrier

Ripple tanka way to show wave behaviors

• Point source• Plane wave• Angled Reflection• Diffraction around a corner• Single slit• Double slit• Doppler effect

Point Source

Angled Reflection

Plane wave

Diffraction around a corner

Single Slit

Doppler effect

Double slit

Your own:

Constructive interference

Motion of source

Towards:- High

frequency- shorter

wavelength

Away:- Lower

frequency- longer

wavelength

DO NOW:1. Which wave phenomena is exemplified by this picture?

2. As the wave propagates, explain what happens to the…

- speed of the wave

- the wavelength of the wave

- the frequency of the wave

- the amplitude of the wave

HW: Castle Learning on Diffraction-Due tomorrow. Counts as a 10pt HW assignment

Aim: How do we recognize various wave behaviors?

Law of ReflectionHow to draw the diagram

• The Law of Reflection states– Angle of incidence is equal to the angle of reflection

ϴi ϴr

Normal Line: A reference line always drawn perpendicular to the surface USE A PROTRACTOR!!!!

Angle of incidence ϴi: angle made between the incident ray and the normal lineIncidence Ray: The light ray on the way

INTO the surface

Reflected Ray: The light ray on the way AWAY FROM the surface

Angle of Reflection ϴr: angle made between the reflected ray and the normal line

Reflection of Light• The bouncing of a wave off of a surface .

– Regular reflection• Bouncing off of a Smooth surface

– Mirrors, ponds– You can see an image of the object

– Diffuse Reflection• Bouncing off of a Rough surface

– The road, leaves, furniture, cloths– You can see light, but no image

Reflection Ray Diagram

Object

Mirror

Normal Line

Incident Rays

Incident Angle

Reflected Ray

Reflected Angle

Eye sees two diverging rays and traces them back

ImageAppears

where the virtual

rays cross

Object Distance Image Distance

Law of Reflection in a PLANE mirror:- Object distance (do)

is equal to image distance (di)

Reflection LabGoals:1. To draw a 2-ray diagram of a single pin image

a. Use this diagram to compare the incident angles to the reflected angle

- Use percent difference to determine if the object distance is the same as the image distance

b. Use this diagram to compare image distance to object distance

- Use percent difference to determine if the object distance is the same as the image distance

1. Draw a line down the middle of the page, perpendicular to the edge of the page

2. Prop the mirror up against the book with the BACK surface of the mirror on your mirror line. Make sure

the cardboard is under the paper

3. Stick the pin in the middle of the page

4. Look in the mirror from the angle and locate the image of the pin in the mirror

Image of the pin

5. Line up the edge of the ruler such that if extended into the mirror, it would run straight into the pin. Trace that line

6. Repeat step 5 from the other side

7. Extend the reflected rays back to the mirror8. Draw a line connecting the object to the place on

the mirror where the reflected rays hit

9. Trace the VIRTUAL rays back behind the mirror. The image appears where the rays meet

10. Use a protractor to construct the normal perpendicular to the mirror at the point where the rays hit the mirror.

11. Measure both incident and reflected rays and compare them using a percent difference

12. Label and measure the object distance and the image distance. Using percent difference, compare

these two numbers

Resultsa. Use this diagram to compare the incident angles

to the reflected angle

b. Use this diagram to compare image distance to object distance

Doppler Effect• The apparent change in a wave’s frequency due to

relative motion between the source and the observer. – Sound– light

Higher frequency Shorter wavelengthHigher pitch

Lower frequency Longer wavelengthLower pitch

Polarization• When a wave vibrates only in one plane

- up-down- left-right

• ONLY transverse waves can be polarized

Classwork

• DO Pg 154-155 #26-47• Read pg 156-158

– This is what we will talk about next period.

Superposition• The piece by piece sum of two waves that meet in

the same place at the same time.

Constructive Interference• When two crests OR two troughs meet to make a

larger crest/trough

Destructive Interference• When a crest and a trough meet to produce nothing

– No light or sound

ResonanceResonance is…When a small amount of energy…

Added at the right frequency…

Produces a large amplitude…

resonance tuning forksglass breaking 1breaking glass 2glass music

When light rays from an object are incident upon an opaque, rough-textured surface, no reflected image of the object can be seen. This phenomenon occurs because of1. regular reflection2. diffuse reflection 3. reflected angles not being equal to incident angles 4. reflected angles not being equal to refracted angles

A typical microwave oven produces radiation at a frequency of 1.0 × 1010 hertz. What is the wavelength of this microwave radiation?1. 3.0 × 10-1 m2. 3.0 × 10-2 m3. 3.0 × 1010 m4. 3.0 × 1018 m

At the instant shown, a cork at point P on the water's surface is moving towardA B C D

Electromagnetic radiation would be classified as 1. a torsional wave 2. a longitudinal wave 3. a transverse wave 4. an elliptical wave

Standing Waves Revisited

Do Now:- What are the three conditions that need to be

met to produce a standing wave?

- An example of a standing sound waveRubens flame tube

HW MAKE A REVIEW SHEET

Sound as Music- What is the relationship between frequency and

pitch?- Think of a trombone, how does the pitch of the

sound change as the length of the slide increases?- Based on this, how is frequency related to

wavelength?• blue man group

– What do you notice about the length of the tubes and the pitch of the waves? Does this confirm your statement above?

Reflection Revisited• Fixed end Reflection

– 180o phase change• Free end Reflection

– No phase change

fixed and free end reflection

Incident Crest

Reflected Trough

Incident Crest

Reflected Crest

ResonanceResonance is…When a small amount of energy…

Added at the right frequency…

Produces a large amplitude…

resonance tuning forksglass breaking 1breaking glass 2glass music

Questions on the videos

• Video 1– What type of wave would be produced in the ping pong balls when hit with the paddle?

– What characteristic of sound does the frequency tell you about?

– When is one tuning fork able to resonate with another? When doesn’t it work?

– How does your radio work?

• Video 2/3– why is the sound of the glass considered resonance?

– What happened to the frequency when he added water?

– What would happen to the sound wave’s wavelength when the water was added?

– What would happen to the glass if he changed the frequency of the sound generator?

• Video 4– What do you notice about the pitches of the sound and the size of the glasses?

– Can you come up with an explanation of the relationship you wrote above?

• Include wavelength and frequency in your explanation

Speed of Sound LabGoals:

1. To use the ideas of resonance, reflection, and standing waves to determine the speed of sound in the classroom.

Setup

Large tube filled with water

Movable tube open on both ends

Tuning fork

L

Procedure1. Choose a tuning fork and note its frequency

in the data able.2. Strike the tuning fork and hold it over the top

of the open tube. Raise the tube until you reach the resonance point (you will hear the sound get loud)

3. Measure the length of the hollow tube that is above the water level.

4. Repeat for 2 other tuning forks.

DataFrequency (Hz)

Length of tube above water (m)

Diameter correction(m)

Wavelength of the sound wave (m)`

Speed of sound (m/s)

DO NOW:1. Name two different media

in this picture.2. What happens to light as it

passes from one medium to the other?

3. Offer an explanation as to WHY you are seeing what you see.

HW: Blue Book Review for test- all of waves up to diffraction: pg

Aim: What is refraction and how do we ?

Refraction• Refraction is the BENDING of a wave as is travels

from one medium to another.• Remember: a wave changes speed when it moves

from one medium to another.

Frequency stays the same when

traveling from one medium to another!!!

Index of Refraction• The index of refraction is similar to the coefficient of

friction.– It tells you how easily (quickly) light travels through a

substance– It has no units– The symbol for index of refraction is n– The formula for the index of refraction is

– c is the speed of light in a vacuum (3x108m/s)– v is the speed of light in the other medium.– The index of refraction is ALWAYS GREATER THAN ONE!

v

cn

Using the Index of Refraction

1. In which medium does light move the fastest?

2. In which medium does light move the slowest?

3. In which two mediums will light have the same speed?

4. What is the speed of light in water?

• We Know– which implies that

– which implies that =f• c and f are constant when changing from one medium to

another so…..= which is written in your reference tables as

Derivations

Example:1. A light wave with a wavelength of 700nm in water enters flint glass.

a. What is the wavelength of the light in flint glass? b. What is the speed of the light in the flint glass?

Snell’s Law• Used to calculate the angle of refraction as a wave

moves from one medium into another.– Low to high index

• Speed decreases• Wavelength decreases• Angle bends towards the normal

– High to low index• Speed increases• Wavelength increases• Angle bends away from the normal

=

Is the speed of this wave increasing or decreasing as it enters shallow

water?

Snell’s LawUse a protractor

1. Air into water

Steps1. Identify both indexes of refraction2. Draw the normal line perpendicular to the surface3. Measure the incident angle (θ1)4. Write your equation and plug in values with units!5. Solve for the unknown angle (θ2 with units)6. Measure the angle from the normal line and construct it using

your protractor

n1 = 1.00

n2 = 1.33

θ1 = 38o n1 = 1.00n2 = 1.33θ2 = ?

==

0.463= =27.6o

Low to High!Light bends

TOWARDS THE NORMAL!

Homework- Make sure lab is complete

- finish packet

Do Now:sheet

AIM:How do we apply Snell’s Law when finding the

index of refraction of a medium?Remember, Snell’s Law:

2211 sinsin nn

Do Now!

Finding the Index of Refraction

Goals: The goals of this lab include

to determine the index of refraction of the unknown block using a graph

Background

write a PARAGRAPH explaining how refraction works and what happens to all the parameters (speed, wavelength, frequency) of a light wave as it moves from one medium to another.

THINK!

based on the do now graph, what do we need to do to determine the index of refraction of a block?

Procedure:

1. Trace the block on a sheet of paper2. Remove the block and construct a normal line close to the

upper right hand corner3. Using colored pencils, construct 5 incident rays at various

angles between 15o and 60o 4. Replace the block, and using a laser beam, sine the light along

one of the incident rays. 5. Locate that ray on the other side of the block and trace that ray

in the same color.6. repeat for all 5 rays7. Remove the block and connect the rays of the same color8. Construct normal lines at each exit point and measure the

incident and refracted angles for each color! 9. Enter all angles in the data table10.Graph sin θ1 vs. sinθ2 (what will the slope of this graph be?)

Finding the Index of Refraction

Refraction Block

Top view

Incident rays.

15o increments

Normal line

Just like in the mirror lab, you will use a laser beam to line up the ray while looking THROUGH the block. Your line of sight needs to be at table level! You can use

pins to help you line it up. Focus on ONE color at a time

After

Refraction Block

Top view

Incident rays.

15o increments

Normal line

DataColor θ1

(degrees)Sin(θ1) θ2

(degrees)Sin(θ2)

Do Now!

Do Now• Light is incident on a flint glass air boundary. The

light enters the air at the following angles– 10o – 20o – 30o – 40o

• Using a ruler and protractor, find the refracted angle for each incident angle. You can use colored pencils to differentiate

Flint glassAir

Critical Angle Lab• Goal:

– To use Snell’s Law and the ideas of refraction to determine the critical angle of water.

– To verify the law of reflection• Setup

water

Air

refracted

reflected

why don’t these rays bend when they enter the water?

Dispersion• The separating of a light ray into its colors

– Caused by the refraction of light– Each color has a slightly different index of refraction

which means that each color bends a little more than the last causing a rainbow

Single Slit Interference• Waves incident on a single

slit– The central (center) maxima

(brightest spot) occurs in line with the single slit.

– Each other small bright spot is a location of constructive interference due to the path difference (1 wavelength) from the lower edge of the slit and the upper edge of the slit

Double Slit Interference• Waves incident on 2 slits produce an interference

pattern with the central maxima between the two slits, and each next maxima decreasing in intensity.

• Due to a path difference betweenthe two slits.

Is light a wave or is light a

particle!?!

Experiment 1:

Think: Light is incident on two closely spaced slits and the pattern is observed on a wall or screen

across the room.

Wave: Water waves incident on two closely spaced openings

Particle: Painted tennis balls are being thrown at a wall through two closely spaced doors.

Young’s Double Slit Experiment

If light was a wave (think water)…

• • • •

If light was a particle (think painted tennis balls)…

• • • •

expectations

Double Slit Experiment

Light behaving like a wave.

Notice the light and dark fringes.

What do the dark spots represent?

What to the light spots represent?

What do the spots with no spots

represent?

Wave moving through a double slit and

exhibiting interference

Young’s Double Slit Experiment:

Shows that light

behaves like a wave

The Photoelectric Effect:

Shows that light behaves

like a particle

The Great DebateWave

• Particle

•

Is light a wave or is light a particle!?!

AIM: How do we describe a particle of light? • Do Now: what behavior shows light is a wave, why? What

behavior shows light is a particle why?

• HW: Blue Book • pg 186-187 #1-11

• Pg 198-200 #1-5, 16-19, 34-35• DUE THURSDAY!

What do we call a particle of light?

A PHOTON!!• A photon is a small ‘packet’ of light

• Any single photon has a fixed, discrete energy. • The intensity of visible light can be increased or

decreased only by changing the number of photons present.

• The same rules hold true for all electromagnetic waves outside the visible range.

Discrete Energy?? • Discrete energy is like money, you can only have integer multiples of

a minimum amount.– For money, what is this minimum amount?

• A photon can only carry integer numbers of a minimum energy– This minimum energy is denoted by Planck’s constant

• h= 6.63x10-34Js• Planck’s constant is modern physics’ version of the

penny• The energy of a photon is determined by its frequency (and

wavelength)

hfE hc

E

UnitsA joule is a large unit of energy. When you are talking about

small electron, we use an electron volt instead

1eV=1.6x10-19JEx1. A photon has 3.5eV of energy. How many Joules of

energy is that?

Ex2. A photon has 4.8x10-19J of energy, how many electron volts is that?

Examples1. A photon of light has a frequency of 2.5x1014 Hz.

- What is the energy of that photon in Joules?- What is the energy of that photon in eV?

2. A photon has a wavelength of 575nm- What is the frequency of that photon?- What is the color of the photon?- What is the energy of that photon in Joules?- What is the energy of the photon in eV?

AIM: How has our understanding of the atom changed over the years?

DO NOW: Draw AND label a diagram of an atom.HW: HW: Blue Book • pg 190-191 #12-34

• DUE TUESDAY

• QUIZ WEDNESDAY!

Atomic Structure

A brief History

Democritus- Greek Philosopher~300BC

• The word atom means smallest piece. Something that can not be divided.

• Atoms are made of the same ‘stuff’ but differ in size and shape

• Atoms are in constant motion• Atoms can combine to form different types of

matter

John DaltonLate 1700s

• All elements are made up of atoms• Atoms of the same element are all the same

but differ from atoms of different elements.• Atoms can group together to form molecules• Chemical reactions are changes in

combinations of atoms, not changes in the individual atoms themselves.

JJ Thomsonlate 1800s

• Measured the charge/mass ratio of an electron.

• Determined that an electron had a negative charge

• Could NOT determine the actual mass or charge of an electron.

• Plum pudding model of the atom

Negative ‘plums’

Positive Goop

Rutherford-Geiger-Marsden1911

• Gold foil scattering experiment– Fired positively charged alpha particles (2 protons and 2

neutrons) at a thin foil of gold.– Most alpha particles traveled straight through

• Most of an atom is empty space– One day, one scattered at a wide angle as if it hit

something massive and dense.• Holds most of the mass of an atom• Must be positively charged

– This massive and dense thing was called the nucleus.– An atom’s diameter is MUCH larger than that of the

nucleus.

Rutherford Scattering Setup

Most particles go straight through. A few scatter and light up the screen at other

angles.

Bohr (Orbital) Model• Electrons orbit around

a central nucleus– The electron orbitals

have definite (discrete) energy levels.

– Electrons can not exist between energy levels.

• Similar to the fact that you can not stand between rungs of a ladder.

Bohr (Orbital) Model• Ground states

– Electrons want to fill the lowest possible levels so that the atom stays stable.

• Excited states– Electrons can ‘jump’ up

energy levels only if the correct amount of energy is absorbed by the electron.

– This amount of energy is determined by the energy difference in the atom’s levels.

The Hydrogen Atom1. What is the energy of the

n=3 energy level in the hydrogen atom?

a. What is this energy in Joules?

2. What is the energy difference between the n=1 and n=4 energy levels?

Hydrogen Absorption SpectrumWhen light is incident on a hydrogen atom, it can

absorb the photons with the correct amount of energy that allow the electrons in the atom to ‘jump’ to their excited states. An absorption spectrum is the rainbow of colors with the colors matching the correct energy jumps missing.

1. Pick one of the missing colors2. Determine a possible frequency of that color using

the RTs3. Calculate the energy a photon of that color4. Convert that photon’s energy into eVs.5. Using your RTs decide which energy level

transition could be caused by that photon.

Hydrogen Absorption Spectrum

Hydrogen Emission Spectrum

Once an electron has reached the excited state by absorbing the correct amount of energy. The electron will stay there for a moment then return back down to the ground state. When the electron falls back to the ground state, it emits a photon with an energy equal to the energy difference between the level it came from and the level it went to.

Hydrogen Emission Spectrum

1. Pick a different color than before.2. Determine a possible frequency of that color using

the RTs3. Calculate the energy a photon of that color4. Convert that photon’s energy into eVs.5. Using your RTs decide which energy level

transition could be caused by that photon.

I was doing some particle physics research and I discovered 7 new elements. I knew that each element was different because

_______________________________________.

I was able to draw diagrams of each element’s energy levels to scale, and I was able to name each element’s spectrum, but I

was not able to match the element’s energy level diagram to its corresponding spectrum.

Your goal is to use the scaled drawing to figure out the letter of that element based on the atomic spectra pictured.

a. Show all calculations in an organized manor including formulas and units.

b. Choose a fourth color for the spectrum and add the corresponding fourth energy level to the element’s

diagram. (it must be drawn to scale)

F

A B C D

E G

Nuclear Physics

Subatomic Forces and Structures

Force Name

Relative Strength

Carrier Carrier symbol

Force Range

Force acts on

Strong Force

Weak Force

Electro-magnetic

Force

Gravitational Force

Zooming in on the World Around Us

Macroscopically•Gravity–holds all objects with mass together (from stars to dust)

•Electromagnetic Force–Holds the (negatively charged) electrons in orbit around the

(positively charged) nucleus of an atom•Strong Force– Holds all the positively charged protons and neutral neutrons

together in the nucleus•Weak Force–Holds all the quarks together in a proton and neutron

Microscopically

Creating Nuclear EnergyMass or energy can never be created or destroyed,

only converted from one to the other!

Fusion• Two smaller elements

(anything below iron) fuse together to create a larger element.

• This is favored by nature because this process releases energy.

Fission • One larger element

(anything above Iron) split apart to create two smaller elements.

• This is favored by nature because this process also releases energy

2mcE

Fusion up Close• For light elements (up to Iron), fusing two elements

together creates a larger element and energy.• This energy comes from the ‘missing’ mass.

– The larger element has a smaller mass then the total mass of the parts that make it up.

– The difference in mass is converted into released energy.

• This only happens in the sun and starts

Fission up Close• An incident neutron causes a large unstable

element to split into smaller elements.• When the element splits, some of the energy used

to hold the large nucleus is released.• This happens in nuclear reactors around the world.

E=mc2

1. Which particle would generate the greatest amount of energy if its entire mass were converted into energy?– electron – proton – alpha particle – Neutron

2. If a proton was completely turned into energy, how much energy would be released?

Mass Defect• The mass of the individual protons and neutrons that make up an

element is larger than the actual mass of the element. • This ‘mass defect’ is converted into the energy needed to hold the

nucleus together.

If the actual mass of the Lithium atom is 6.941u, - What is the mass defect in u- What is the binding energy in MeV?- What is the binding energy in Joules?

The Standard Model of Particle Physics

Things smaller than protons and neutrons

Classification of Matter

Protons and neutrons have 3 quarks, so they are Baryons!

Quarks

• A proton is made up of two up quarks and a down quark (uud)

• A neutron is made up of two downs and an up (udd)

Leptons

• Electrons are leptons!

Antiparticles

• Antiparticles have the same mass as their particle ‘buddies’ just the opposite charge and quark make up.

• If a particle and an antiparticle collide, they annihilate each other and all the mass is converted into energy.1. What is the quark make up of an antiproton?

2. If a neutron and antineutron collide and annihilate each other, how much energy is released in Joules?

Example Questions for Modern Physics Unit.

• DO NOT LOSE THIS PACKET!

Name ______________

Young’s Double Slit Experiment

If light was a wave (think water)…

• • • •

If light was a particle (think painted tennis balls)…

• • • •

Expectations

The Photoelectric Effect

If light was a wave (think water hitting the fence)…

• • • •

If light was a particle (think bowling balls hitting the fence)…

• • • •

Expectations

The work function of a certain photoemissive material is 2.0 electronvolts. If 5.0-electronvolt photons are incident on the material, the maximum kinetic energy of the ejected photoelectrons will be

1. 7.0 eV 2. 5.0 eV 3. 3.0 eV 4. 2.5 eV

Electromagnetic radiation of constant frequency incident on a photosensitive material causes the emission of photoelectrons. If the intensity of this radiation is increased, the rate of emission of photoelectrons will

1. decrease 2. increase 3. remain the same

----------------------------------------------------------------------------------------------------------------------------------------------------------------------A joule is a large unit of energy when you are talking about small electrons. We use an electron volt instead

1eV=1.6x10-19J

Ex1. A photon has 3.5eV of energy. How many Joules of energy is that?

Ex2. A photon has 4.8x10-19J of energy, how many electron volts is that?

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1. A photon of light has a frequency of 2.5x1014 Hz. - What is the energy of that photon in Joules?- What is the energy of that photon in eV?

2. A photon has a wavelength of 575nm- What is the frequency of that photon?- What is the color of the photon?- What is the energy of that photon in Joules?- What is the energy of the photon in eV?

The Hydrogen Atom1. What is the energy of the n=3 energy level

in the hydrogen atom?

a. What is this energy in Joules?

2. What is the energy difference between the n=1 and n=4 energy levels?

1. Pick one of the missing colors

2. Determine a possible frequency of that color using the RTs

3. Calculate the energy a photon of that color

4. Convert that photon’s energy into eVs.

5. Using your RTs decide which energy level transition could be caused by that photon.

Hydrogen Absorption Spectrum

I was doing some particle physics research and I discovered 7 new elements. I knew that each element was different because they all had different atomic spectra. I was able to draw diagrams of each element’s energy levels to scale, and I was able to name

each element’s spectrum, but I was not able to match the element’s energy level diagram to its corresponding spectrum.

Your goal is to use the scaled drawing to figure out the name of that element based on the atomic spectra pictured below.

a. Show all calculations in an organized manor including formulas and units.

b. Choose a fourth color for the spectrum and add the corresponding fourth energy level to the element’s diagram. (it must be drawn to scale)

Force Name Relative Strength

Carrier Carrier symbol

Force Range Force acts on

Strong Force

Weak Force

Electro-magnetic Force

Gravitational Force

Mass Defect• The mass of the individual protons and neutrons that make up an element is larger than the actual mass

of the element. • This ‘mass defect’ is converted into the energy needed to hold the nucleus together.

If the actual mass of the Lithium atom is 6.941u, - What is the mass defect in u

- What is the binding energy in MeV?

- What is the binding energy in Joules?

E=mc2 1u=931MeV1. Which particle would generate the greatest amount of energy if its entire mass were converted into energy?

– electron – proton – alpha particle – Neutron

2. Approximately how much energy would be generated if the mass in a nucleus of an atom of were converted to energy? [The mass of is 2.0 atomic mass units.]- 3.2 × 10-10 J- 1.5 × 10-10 J- 9.3 × 102 MeV- 1.9 × 103 MeV

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Antiparticles have the same mass as their particle ‘buddies’ just the opposite charge and quark make up.If a particle and an antiparticle collide, they annihilate each other and all the mass is converted into energy.

1. What is the quark make up of an antiproton?

2. If a neutron and antineutron collide and annihilate each other, how much energy is released in Joules?