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In this worksheet, students will be challenged to look not just at how shadows form but the effect of moving the light source or the object creating the shadow.

Key stage:  KS 2

Curriculum topic:   Light

Difficulty level:

### QUESTION 1 of 10

In your previous work on shadows you have found out that when light from a luminous source falls on an object, like a vase, that object blocks some of the light rays which then bounce off it. This means that they don't reach the area behind the object and that causes an area of darkness to form which we call a shadow.

In this worksheet we'll consider how the shadow formed is affected by where the object is in relation to the light.

Here's a picture of Fido and his shadow on the ground.

In what ways do you think his shadow would be different if Fido was stood on his garden wall looking at his shadow further away below him on the path?

Tick all the answers you think are right.

his shadow would be the same size

Shadows move their position as the direction of the light changes.

Here's a picture of a plastic duck being lit up by a torch:

Look at the three possible shadows compared to where the torch is.

Which one do you think is correct?

A

B

C

Imagine that the duck in question 2 was lit not by a torch but by two different things: the Sun and the Moon.

Do you think that the shadow would get sharper or dimmer compared to that made with a torch?

Match the result to the light source.

## Column B

Sun
Sharper
Moon
Dimmer

As you know the Sun moves across the sky during the day. As it does so the shape of the shadows it makes changes.

Here are five pictures of a house, its shadow changing with the position of the Sun in the sky:

Match the picture to the time of day you think it represents according to where the Sun is and the shape of its shadow. By the way, you're looking south!

## Column B

A
12:00/12pm
B
15:00/3pm
C
06:00/6am
D
18:00/6pm
E
09:00/9am

Which of the following do you think will make the most distinct and clearest shadows?

Tick all the ones you think will.

greenhouse

paper hat

car

glass of water

Here's a picture of a torch being shone at a vase:

A shadow falls on the screen behind.

Here is a list of possible ways in which the shadow could be made to be BIGGER - tick all the ones you think are correct.

move the vase towards the light

move the vase away from the light

move the screen towards the vase

move the screen away from the vase

move the torch towards the vase

move the torch away from the vase

Mrs. Bates was investigating how the size of shadows changes with her science class. They were using a teddy bear and a torch:

Mrs. Bates asked her students to move the teddy bear towards the screen, measuring the distance to the screen and the size of the shadow as they did so.

Here are their results:

 Distance to screen/cm Size of shadow/cm 50 40 30 20 10 0 55 48 41 34 27 20

Looking at the results by how much does the image size change each time the students move the teddy bear 10cm closer to the screen?

7cm more

7cm less

7mm less

Mrs. Bates helped her class to produce a line graph of their results:

She then asked her students to write down what they thought the graph showed them. Here is what three of them wrote.

Tyler: "as we moved the teddy bear towards the screen it got bigger."

James: "as the teddy bear moved further from the light the image got smaller."

Jessica: "the shadow was smaller when the teddy bear was closer to the screen."

Who do you agree with most?

Tyler

James

Jessica

Here is their graph again:

Looking at the graph what do you conclude about how the size of the shadow changes as the teddy bear is moved towards the screen?

As the teddy bear moves towards the screen the shadow gets smaller

As the teddy bear moves towards the screen the shadow gets bigger

As the teddy bear moves towards the screen the shadow stays the same

Here's the graph once more:

How big do you think the teddy bear was?

20cm

34cm

55cm

• Question 1

Here's a picture of Fido and his shadow on the ground.

In what ways do you think his shadow would be different if Fido was stood on his garden wall looking at his shadow further away below him on the path?

Tick all the answers you think are right.

EDDIE SAYS
When the object making the shadow moves further from the surface where the shadow is falling, the shadow gets bigger and thus fatter. Go on, you try it: hold your hand in front of the light so it falls on paper - now move the paper further from your hand ... see?
• Question 2

Shadows move their position as the direction of the light changes.

Here's a picture of a plastic duck being lit up by a torch:

Look at the three possible shadows compared to where the torch is.

Which one do you think is correct?

B
EDDIE SAYS
From where the torch is the shadow must fall in line with the duck and the light source, so B must be the one. A would form if the light was directly above and C if it was straight in front.
• Question 3

Imagine that the duck in question 2 was lit not by a torch but by two different things: the Sun and the Moon.

Do you think that the shadow would get sharper or dimmer compared to that made with a torch?

Match the result to the light source.

## Column B

Sun
Sharper
Moon
Dimmer
EDDIE SAYS
The Sun's light is very strong so a clear shadow will form beneath it. The light from the Moon is reflected from the Sun so is nowhere near as strong and so the shadow won't be as clear.
• Question 4

As you know the Sun moves across the sky during the day. As it does so the shape of the shadows it makes changes.

Here are five pictures of a house, its shadow changing with the position of the Sun in the sky:

Match the picture to the time of day you think it represents according to where the Sun is and the shape of its shadow. By the way, you're looking south!

## Column B

A
15:00/3pm
B
09:00/9am
C
18:00/6pm
D
12:00/12pm
E
06:00/6am
EDDIE SAYS
Looking south the Sun rises in the east (on the left) and works its way across the sky from there - notice how the shadow changes accordingly.
• Question 5

Which of the following do you think will make the most distinct and clearest shadows?

Tick all the ones you think will.

car
EDDIE SAYS
Anything that's really opaque makes a good shadow as it won't allow any light through. Paper's a little translucent and both the other two are mostly transparent.
• Question 6

Here's a picture of a torch being shone at a vase:

A shadow falls on the screen behind.

Here is a list of possible ways in which the shadow could be made to be BIGGER - tick all the ones you think are correct.

move the vase towards the light
move the screen away from the vase
move the torch towards the vase
EDDIE SAYS
Try it yourself with a light in your room, or the Sun, and your hand and a piece of paper: you'll see that when you move your hand towards the light the shadow gets bigger. It also does when you move the paper away from your hand or when you move the light (or the Sun!!) closer to your hand.
• Question 7

Mrs. Bates was investigating how the size of shadows changes with her science class. They were using a teddy bear and a torch:

Mrs. Bates asked her students to move the teddy bear towards the screen, measuring the distance to the screen and the size of the shadow as they did so.

Here are their results:

 Distance to screen/cm Size of shadow/cm 50 40 30 20 10 0 55 48 41 34 27 20

Looking at the results by how much does the image size change each time the students move the teddy bear 10cm closer to the screen?

7cm less
EDDIE SAYS
You can see that the results change by 7cm each time. As the distance to the screen DECREASES the shadow size DECREASES as well (in proportion), meaning that it gets 7cm smaller with every 10cm move closer.
• Question 8

Mrs. Bates helped her class to produce a line graph of their results:

She then asked her students to write down what they thought the graph showed them. Here is what three of them wrote.

Tyler: "as we moved the teddy bear towards the screen it got bigger."

James: "as the teddy bear moved further from the light the image got smaller."

Jessica: "the shadow was smaller when the teddy bear was closer to the screen."

Who do you agree with most?

Jessica
EDDIE SAYS
Although Jessica's answer could be a little more detailed, it's closest to what they found out. James is nearly correct: the SHADOW got smaller as the teddy moved further from the light (and closer to the screen) but he incorrectly called it an image. Tyler said "it got bigger" - what does he mean by "it"?
• Question 9

Here is their graph again:

Looking at the graph what do you conclude about how the size of the shadow changes as the teddy bear is moved towards the screen?

As the teddy bear moves towards the screen the shadow gets smaller
EDDIE SAYS
It's clear from the results that as the distance to the screen decreases, so does the size of the shadow - that makes sense: less of the light is being blocked as the teddy bear is further from it, so the shadow (area of darkness behind it) is smaller.
• Question 10

Here's the graph once more:

How big do you think the teddy bear was?

20cm
EDDIE SAYS
Basically when the distance to the screen is 0cm the teddy bear is touching the screen. At that point its shadow will be the same size as the bear: 20cm.
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