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TRANSCRIPT
NAME ____________________ FORM ________
International 1/Gymnasium Science
Light
6E-WS1 LUMINESCENT OBJECTS
Aim: Identify luminous objects
Luminescent Object: An object that produces its own light.
Put a circle around the following objects that you think are luminescent objects.
StarTree Glow worm Television
MoonJupiter Fire
Lake
Mirror Clouds Light Bulb
Glow in theTorch
Sun Camera Flashdark stars
Did you get any wrong? If you did then say why.
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Did you know......Some animals can
produce their own light. This is called BIOLUMINESCENCE. It is normally produced by animals that live in dark environments such as caves, the deep sea or even just at night.
The Anglerfish has a glowing 'bait' that it uses to lure in its prey, they live very deep down in the ocean where there is no light
6E-WS2 DRAWING LIGHT RAYS
Aim: To be able to correctly draw a scientific light ray
Don't Forget:
• Light rays are always drawn as a straight line with a pencil and ruler.
• They always have one arrow per straight line to show the direction it is travelling in.
• The light ray always travels away from the light source.
• When a light ray is reflected then the reflected ray must start at the exact same point as the incident (incoming) ray has stopped at.
How do we see luminous objects? - Complete the picture
Light Source Observer
How do we see non-luminous objects? - Complete the picture
Light Source Observer
Non-luminous Object
6E-WS2 DRAWING LIGHT RAYS
How do we see colour?
Fact 1: White light (from a light bulb or the sun) is made up of every colour!
Fact 2: The colour of an object is the colour of the light that it reflects - it will absorb all other colours.
Complete these diagrams:
Light Source
Common Mistake!
Light does not travel out of our eyes! We are not robots with laser vision!
Observer
Red Object
Light Source Observer
White Object
Light Source Observer
Black Object
6E-WS3 CLASSIFYING TRANSPARENT, TRANSLUCENT AND OPAQUE OBJECTS
Aim: To be able to correctly identify a variety of transparent, translucent and opaque objects
Write down your own definitions for:
Transparent: .................................................................................................
Translucent: .................................................................................................
Opaque: .................................................................................................
• Look around the room and classify as many objects as you can find into the following categories
Transparent Translucent Opaque
6E-WS4 THE SPEED OF LIGHT
Aim: To be able to use real world values and the speed/distance/time equation to work out the speed of light.
The speed of light is a universal speed limit. Nothing can ever go faster than the speed of light!
The speed of light: 300,000,000 meters per second (m/s) or 300,000 km/s
In order to use the speed of light you need to understand how to work out times and distances when given a speed.
• A speed is just a measure of how far you travel in a certain time. for example meters per second or kilometers per hour
We can put this into an equation: Speed = Distance / Time
We can also rearrange the equation to find out distances and speeds. An easy way to remember this is the DST triangle.
• Cover up wha
t you want to find, for example distance (the D) and you ar
e left with S x T
Distance = Speed x Time
• Cover up the T (time) and you are lef
t with D over S or D/S, the slash means divide.
Time = Distance / Speed
Q1) The Sun is 150,000,000,000 meters from the Earth. How long does it
take for the light to reach us from the sun? Show your workings and give your time in minutes.
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Q2) It takes light 5 hours 28 minutes and 30 seconds to reach Pluto from the Sun. How faraway is Pluto? Don't forget to convert the time into seconds.
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6E-WS5 WHAT TYPE OF SHADOW DOES IT CAST?
Aim: To be able to shine a light through different objects, identify how to keep it a fair test and makeobservations.
Task: Shine a light through a variety of objects and compare the shadow to that on the chart.
Identifying the Variables Really think about the control variables!
Independent ..............................................................
Dependent ..............................................................
Control ............................................................................................................
Equipment
• Light source• Variety of thin objects• White paper• 1 meter ruler
Method
1. Collect equipment
2. Place the light source 30cm from the object and the object 30cm from the white paper3. Observe the shadow that is created and compare it to the chart
Prediction
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Results
Object Shadow Observationsshade (1-10)
6E-WS5 WHAT TYPE OF SHADOW DOES IT CAST?
Q1) What type of objects let the most light pass through them? Why do you think this is?
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Q2) What type of objects let the least amount of light pass through? Why?
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Q3) Why do you think it was important to use objects of the same thickness and ensure that the light-object-paper distance remained the same?
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Q4) Is there anything else that you can think of that might affect the shadow shade? How could you solve this problem?
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Q5) What do you think would happen to translucent object shadows if the light-object-paper distance was reduced? Why?
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Q6) What happens to the shadows of coloured transparent/translucent objects?
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Q7) Do completely transparent objects leave behind a shadow? Why do you think this is?
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6E-WS6 SOLAR ECLIPSES
Aim: To use the internet to research about solar eclipses
Solar eclipses are rare events tha
t only happen occasionally. A total Sola
r eclipse generally only happens every 5
0 years in the U.K and about once a year
in the world. The frequency with which t
hey happen is not set so the time in betw
een each one is different every time.
Q1) What is a Solar eclipse?
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Q2) What is the difference between a partial and a total eclipse?
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Q3) During a total solar eclipse the moon exactly covers the Sun, meaning that in the sky they appear to be the same size, are they really the same size? Why do they appear to be the same size?
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Q4) What famous theory was proven during the 1919 Solar eclipse? Explain briefly how it was proven.
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6E-WS7 THE LAW OF REFLECTION
Aim: To be able to correctly set up apparatus and accurately measure the angle of reflection.
Task:Reflect a light ray off a plane mirror and
compare the angle of incidence with
the angle of reflection.
Keywords:
Plane mirror - A flat mirror, drawn as a straight line with dashes underneath.
Normal - An imaginary line that is draw straight up from where the light ray
hits the mirror.
Angle of incidence - The angle between the normal and the incident light ray.
Angle of reflection - The angle between the normal and the reflected light ray.
Equipment:
• Plane mirror• light ray box with single slit• pencil, ruler and protractor• Plain white paper
Method:
1. Collect your equipment and set it up so that the single slit is in front of the light ray box and produces a single thin light ray.
2. Place the mirror on its side and angle the beam so that it reflects off the mirror. Make sure that the end of the light ray box is also on the paper.
3. Using a pencil place a single dot where the light ray leaves the light ray box, a dot where it hits the mirror and finally a dot about 10cm on along the reflected light ray.
4. Being careful not to move the mirror, draw a line using a pencil along the surface of the mirror.
5. Join up the dots in the order you placed them and draw in the normal, using a ruler, as a dotted line.
6. Using a protractor, measure the angle between the incident ray and the normal and the reflected ray and the normal, these will be the angle of incidence and the angle of reflection respectfully.
7. Repeat for different angles.
6E-WS7 THE LAW OF REFLECTION
Results: Conclusion:
What have you found out from this investigation?θi θr
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Were any angles of incidence different from the correlatingangle of reflection? If so why do you think this was the case?
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Draw a perfect light ray diagram where θi = 45° and θr = 45°
THE LAW OF REFLECTION!!
The angle of reflection is ..................... the.................... as the angle of incidence.
6E-WS8 REFLECTION ON REFLECTION
Aim: To be able to use knowledge of reflection to answer a variety of questions
Questions on reflection
Q1) Ambulances have the word ‘ AMBULANCE’ written backwards, why do you think this is?
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Q2) White objects reflect every colour of light, yet we canno t see reflections in them.
Have a look at the following pictures.
By referring to the picture explain why you think that we can see reflections in smooth shiny surfaces but not on white rough surfaces.
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SUPER SCIENCE QUESTION!!
What colour do you think a mirror is? This is a tough question with multiple answers so have a think. Try to back your answer up with an explanation.
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6E-WS9 REFRACTION IN TRANSPARENT BLOCKS
Aim: To be able to correctly set up scientific equipment and measure the refraction of light through aTransparent object.
Equipment:
• Perspex/glass block• Light ray box with single slit• White paper, pencil, ruler and protractor
Method:
1. Place the glass block on the table and place the protractor on the side of the block.
2. Shine the light ray so that it hits the block at 50° to the normal.
3. Make a pencil point where the light leaves the light ray box, where it hits the transparent block, leaves the transparent block and then 10cm on along the light ray from the point of exit, all the while being very careful not to move the transparent block.
4. Carefully draw around the transparent block ensuring it is not moved.
5. Join up the pencil dots with a ruler.
6. Measure the angles that the light ray makes to the normal when it is inside the transparent block and also when it has left the block.
7. Repeat for an angle of 0° (straight onto the block).
8. Try to find an angle or position that allows the light ray to fully reflect off the inside of the transparent block.
Results: Draw what you see
The light ray at 50° to the normal - Complete the diagram with what you observe, don't forget to draw in the normal when the light ray leaves the glass block. Make sure that you use the same angles that you measured.
50°
6E-WS9 REFRACTION IN TRANSPARENT BLOCKS
The light ray at 0° to the normal (straight on) - Complete the diagram with what you observe.
0°
Use a ruler and a pencil to draw a diagram of a position between the light ray box and transparent block that will cause the light ray to bounce off the inside of the block once it has already entered. How many times can you get the light ray to reflect internally?
6E-WS9 REFRACTION IN TRANSPARENT BLOCKS
Conclusion:
Q1) When the light ray entered the transparent block did it move closer to the normal or away from the normal?
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Q2) When the light ray left the transparent block did it move closer to the normal or away from the normal?
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Q3) What happened to the light ray when it was shone straight on to the transparent block?
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Q4) Did you notice anything about the angles made when the light ray entered and left the block?
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Q5) Did you notice anything about the angles made by the light ray and the normal when it was inside the transparent block?
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Facts about Refraction - Fill in the Blanks
For refraction to happen a light ray must pass through a
_ _ _ _ _ _ _ _ _ _ _ medium, examples of transparent mediums are air, glass and _ _ _ _ _ . When the light ray passes from a less dense medium (for example _ _ _ ) into a more dense medium (for example
_ _ _ _ _ ) then the light ray will slow down, which causes it to bend
_ _ _ _ _ _ _ the normal. When the light ray passes from a more dense medium to a less dense medium (for example glass into air) then it will_ _ _ _ _ _ _ and bend away from the normal.
Speed up Water TransparentTowards AirGlass
6E-WS10 FISHHUNTERS
Aim: To be able to use knowledge of refraction to answer questions.
Hunting fishIn some parts of the world people use spears in order to catch fish. Quite often when people try to do it for the first time they will miss, even if the fish is only a meter or so away. They quickly learn to not aim at the fish but just slight away from it.
Q1) Why do you think this is?
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Q2) Where do you think they will have to change their aim to? Above the fish, below the fish, to theleft or to the right? Explain your answer using scientific terms.
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Fish Hunting BugsIn a reversal of roles there is a very special fish called the Archer Fish that does the opposite and hunts bugs outside the water. It squirts a jet of water, that is accurate up to 2 meters and knocks bugs off leaves, to fall into the water and be eaten.
Q3) What difficulties might this fish have when aiming? Can you think of two factors it will have to take into account?
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If you can answer this then you are amazing! You may need to research it on the internet though. Think about refraction and total internal reflection
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6E-WS11 PERISCOPES
Add light rays to the two periscope diagrams below
Do you know......
• What a luminescent object is?• How to draw a light ray directly?• How to draw a light ray reflected?• What it means when light is scattered?• How we see coloured objects?• What colours do coloured objects reflect and absorb?• What colours do white and black objects reflect and absorb?• The definitions of transparent, translucent and opaque?• How a shadow forms?• what affects the size of a shadow?• What type of objects cast see through or coloured shadows?• The law of reflection?• Why we can see a clear image in a mirror?• How to correctly draw a reflection diagram?• What refraction is?
• Which way will a light ray bend when it goes from air into glass/perspex/water?
• Which way will a light ray bend when it goes from glass/perspex/water into air?
If you answer NO to any of these then go back over your work and revise!