PL RS P4L43 Revision 11 WS

Primary 4

Rocket Science

Name __________________________________________________
Tutor
Topic LESSON 43 (REVISION - LIGHT)

__________________________________________________

LESSON 43 (REVISION - LIGHT)

Primary 4: Rocket Science

Lesson Outline

• Notes
• Activity 1: Fun facts
• Activity 2: MCQS
• Activity 3: Open-ended Questions
• Activity 4: Science in daily life

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Primary 4: Rocket Science

REVISION – Light and shadows: Fill in the blanks

• We can see an object because light falls on it and the rays are ____________
into our eyes.

• We can see light coming from its source when we are at the other end because
light travels in a ___________ _________.

• We cannot see light coming from its source when we are at the other end when
the path of light is ______________. This is because light travels in a straight
line and cannot go around the obstacle.

• A ________________, or an area of darkness, is formed when an object
blocks all or some light. Since light travels in a straight line, it cannot go around
the object and light up the area.

• The nearer an object is to a light source, the ____________ but less sharp its
shadow will be.

• The further an object is from a light source, the ___________ but sharper its
shadow will be.

• The position of a shadow is opposite to the location of the light source.

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Primary 4: Rocket Science

REVISION – Light and shadows

To create a bigger shadow To create a smaller shadow
1) Move the object closer to the 1) Move the object further away from to

torch. the torch.
2) Move the torch closer to the 2) Move the torch further away from the

object. object.
3) Move the screen away from 3) Move the screen closer to the object.

the object.

A light sensor can measure the amount of light passing through an object.
The measurements taken can be recorded in a datalogger connected to the
light sensor.
The measurements can be transferred from the datalogger to a computer, and
shown as a graph.

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Primary 4: Rocket Science
Activity 1 – Fun facts: How an “invisibility cloak” works

https://www.youtube.com/watch?v=7W5T-qOQF50
Discussion Questions:
1) How are we able to see things around us?
2) Are we able to see anything in a completely dark room? Why is this so?
3) How do items appear “invisible” at the viewing point when they are
placed at the invisible points?
4) How do you think lenses in eyeglasses correct a person’s vision?

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Primary 4: Rocket Science

Activity 2 – MCQs

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Primary 4: Rocket Science

1. Look at the picture below.
Girl

Direction of light

Which one of the following correctly explains why the girl can see the book
on the table?
(1) (2)

(3) (4)

()

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Primary 4: Rocket Science

2. Study the diagram below.

Torch

Screen

Ball

What can be done to make the shadow of the ball appear smaller on the
screen?

A Move the ball closer to the torch
B Move the torch closer to the ball
C Move the ball further from the torch
D Move the torch further from the ball

(1) A and B only
(2) C and D only
(3) A, C and D only
(4) B, C and D only

()

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Primary 4: Rocket Science

3. Jane shines a torch on the metal container as shown below.

• (4)

torch metal container

screen

Which one of the following shows the shadow of the metal container cast
on the screen?

(1) (2)

(3) (4)

()

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Primary 4: Rocket Science

4. The diagram below shows the shadow of the same vertical pole at different
times of the day.

A BC D

Which one of the poles is likely casting a shadow at 12 noon?

(1) A

(2) B

(3) C

(4) D ( )

5. The set-up below shows light shining on an orange.

torch orange screen

Which of the following would likely be seen on the screen?

()

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Primary 4: Rocket Science

6. Four sheets A, B, C and D of similar thickness, are made of different
materials. Sheet B has a square hole in its centre. Sheet C has a triangular
hole in its centre.

ABCD
The four sheets are placed in a straight line. A lighted torch is shone on the
sheets as shown below.

The diagram below shows the shadow that is cast on the screen.

screen

ABCD

Which of the following is correct? ( )

A Sheet A allows most light to pass through 11
B Sheet B is translucent
C Sheet C is translucent
D Sheet D is opaque

(1) A only
(2) B and C only
(3) A and C only
(4) A and D only

Primary 4: Rocket Science

7. Qiara had four plastic frames, A, B, C and D, as shown below.

15 cm

15 cm 15 cm 15 cm

frame B frame C frame D

She hung the frames between a lamp and a screen as shown.

screen lamp

Z
frames

The shadows formed on the screen are shown below.

Which frame was hung at position Z?

(1) A
(2) B
(3) C
(4) D

()

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Primary 4: Rocket Science

8. Peter carried out an experiment as shown below. He wanted to find out if the
distance between the light source and an object affects the height of its
shadow on a screen.

light distance screen
source between
height of
light shadow
source object cast on
screen
and
object

The table shows the results of her experiment.

Distance between light source and 10 15 20 25
object (cm)

Height of the shadow cast on the screen 32 27 25 23
(cm)

Based on this experiment, the height of the shadow cast on the screen

_____________________.

(1) decreases when the distance between light source and object
increases

(2) decreases when the distance between light source and object
decreases

(3) remains unchanged when the light source is placed further to the
object

(4) increases when the light source is placed further away from the object

()

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Primary 4: Rocket Science

9. An experiment was conducted to find out if light can pass through four
similar sheets, A, B, C and D made of different materials.
The sheets were arranged in two set-ups, P and Q, as shown.

set-up P set-up Q

The distance travelled by the light for each set-up was measured and the
results are shown below.

Distance
travelled by
light (cm)

Set-up P Set-up Q
Which of the following correctly describes sheets A, B, C and D?

Does it allow light to pass through?

ABCD

(1) no not sure yes no

(2) yes no yes not sure

(3) not sure yes no yes

(4) yes no not sure no

( )

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Primary 4: Rocket Science

10. John walked in a straight line from A to C as shown in the diagram below.
brightly-lit lamp

A BC
The distance between A and B is the same as the distance between B and
C.
Based on the information above, which of the following graphs shows how
the length of John’s shadow changes during his walk?
(1) (2)

(3) (4)

()

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Primary 4: Rocket Science

11. The shadow of an object is as shown below.
Which of the following objects could not have possibly formed the above
shadow?

(1) (2)
(3) (4)

()

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Primary 4: Rocket Science

12. Joey conducted an experiment using a light sensor to measure how much
light can pass through four different materials A, B, C and D.

The table below shows the reading measured by the light sensor when
each material was placed in front of the torch.

material amount of light measured by
light sensor (lux)
A 0
B
C 120
D
860

450

Which material, A, B, C or D, is likely to be a metal?
(1) A
(2) B
(3) C
(4) D

( )

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Primary 4: Rocket Science

Activity 3 – Open-ended Questions
1. Jack carried out an experiment using 4 sheets of the same thickness but

made of different materials P, Q, R and S. He placed each sheet in front of
a light bulb, one at a time, as shown below.

A light sensor connected to a datalogger is used to record the amount of
light passing through each sheet. Jack recorded the results in the table
below.

Material Amount of light detected
(units)
P 12
Q
R 0
S
85

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(a) Based on the results in the table, suggest one property of sheet Q. [1]

________________________________________________________

(b) Explain how using sheets of the same thickness helps Jack make his

experiment fair. [1]

________________________________________________________

Jack wanted to use one of the above materials to make a container to keep
his pet. This container must allow Jack to see his pet very clearly.

(c) Which material P, Q, R or S will be the most suitable for his choice?

Explain your answer. [2]

_______________________________________________________

_______________________________________________________

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Primary 4: Rocket Science

2. Mundeep was walking along a brightly-lit corridor. At first, he noticed that
his shadow was behind him.

(a) As he moved forward, he realised that his shadow was now in front of

him. Give a reason why this happened. [1]

_______________________________________________________
_______________________________________________________

(b) When he reached the lift lobby, he noticed that he now has two

shadows. Give a reason why this happened. [1]

_______________________________________________________
_______________________________________________________

(c) What would happen to his shadow if the lights were to become
dimmer? Put a tick () in the box to indicate the correct answer. [1]

His shadow will become darker.
His shadow will become fainter.
Nothing will happen to his shadow.

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Primary 4: Rocket Science

3. Jessica placed a ball to form shadow X on the screen as shown below.

She then moved the torch 30 cm away from the ball to form a new shadow, Y.

After that, she moved the ball 30 cm towards the torch again to form another
shadow, Z.

(a) Arrange the shadows, X, Y and Z, from the smallest to the largest in

the space below. [1]

Smallest Largest

_____________ , __________ , ____________

(b) Explain how the shadow of the ball is formed on the screen. [1]

______________________________________________________

______________________________________________________

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Primary 4: Rocket Science

4. The set-up below uses a light sensor to count the number of boxes on a

moving belt that moves at a constant speed. The boxes are spaced equally

apart on the belt. light sensor

direction the belt is connected to
moving a data logger

moving belt boxes

light source

When a box gets in between the light source and the light sensor, it
blocks the light from reaching the sensor. The data recorded is shown in
the graph below.

Brightness (unit)

0 5 10 15 20 25 30 35 40 45 Time (s)
cardboard glass
(a) Circle the correct answer below. [1]

The boxes could be clear
made of plastic

(b) Based on the graph, how many boxes passed through the sensor in
45 seconds? Explain your answer, making reference to the graph. [2]

________________________________________________

________________________________________________

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Primary 4: Rocket Science

Activity 4 – Science in daily life: What is colour?

https://www.youtube.com/watch?v=UZ5UGnU7oOI
Discussion Questions:
1) What is colour?
2) What are the lowest and highest frequency of light that we can see?
3) Explain what happens to visible spectrum of light when we are
looking at a yellow pencil. (2.18 min)
4) Why is it not a good idea to wear a black t-shirt to an outdoor event
on a hot sunny day?

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