Weekly Assessment 3 — Light & Shadows

Name

Class

Date

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Instructions: This assessment has 2 sections. Answer all questions. Section A has 10 multiple-choice questions (2 marks each). Section B has 4 structured questions. Write your answers in the spaces provided. Total: 60 marks.

Key Concepts Covered

Sources of light (luminous vs non-luminous objects)
How we see objects — light reflected into our eyes
Shadows — how they form, and how their size/position change
Transparent, translucent, and opaque materials
Reflection of light and mirrors

Section A

Multiple Choice Questions

[2 marks each · 20 marks]

Question 1

Which of the following is a source of light?

AThe Moon

BA mirror

CA lit candle

DA white wall

Question 2

Which of the following statements about a mirror is correct?

AIt gives off light and reflects light

BIt reflects light but does not give off light

CIt gives off light but does not reflect light

DIt does not give off light and does not reflect light

Question 3

A ball is placed between a torch and a white screen. A shadow is formed on the screen because the \_\_\_\_\_\_.

Aball blocks the light

Bscreen reflects light

Cball gives off light

Dscreen absorbs light

Question 4

An opaque object was placed between a torch and a screen. At which position should the object be placed to form the largest shadow?

APosition A

BPosition B

CPosition C

DPosition D

Question 5

Three objects — K, L and M — were placed between a torch and a screen, one at a time:

K — No shadow was formed on the screen
L — A dark shadow was formed on the screen
M — A faint shadow was formed on the screen

Which row correctly identifies the type of material for each object?

	K	L	M
(1)	Transparent	Opaque	Translucent
(2)	Translucent	Transparent	Opaque
(3)	Opaque	Transparent	Translucent
(4)	Transparent	Translucent	Opaque

A(1)

B(2)

C(3)

D(4)

Question 6

The diagram below shows the shadow of a tree at a certain time of day.

At what time of day would the shadow of the tree be the longest?

A10 a.m.

B12 noon

C2 p.m.

D6 p.m.

Question 7

John is reading a book in a well-lit room. Which statement explains how John sees the book?

ALight is reflected from the book to his eyes

BLight travels from his eyes to the book

CThe book emits light into his eyes

DLight from his eyes reflects off the book

Question 8

A ball was dropped between a light source and a light sensor. As the ball bounced, it bounced lower each time. The light sensor recorded the amount of light detected.

Which statement about the amount of light detected by the light sensor is correct?

AIt decreased each time the ball bounced

BIt increased each time the ball bounced

CIt stayed the same

DIt became zero when the ball stopped

Question 9

Kailey set up three cardboard sheets with holes in them to investigate how light travels. She could see the candlelight through the holes only when the three holes were in a \_\_\_\_\_\_.

Azigzag pattern

Bcurved line

Cstraight line

Dcircle

Question 10

Ali moved an object closer to the torch while keeping the screen in the same position. What happened to the size of the shadow?

AIt became smaller

BIt became larger

CIt stayed the same

DIt disappeared

Section B

Structured Questions

[10 marks each · 40 marks]

Question 11

Four students measured the amount of light passing through four different objects — R, S, T and U — using a light sensor connected to a datalogger.

Object	Amount of light recorded (units)
R	200
S	0
T	75
U	500

(a) Which object does not allow any light to pass through? [1]

(b) Classify each object as transparent, translucent or opaque. [3]

Question 12

Ali wanted to find out how the distance between the light source and the object affects the size of the shadow. He carried out the experiment in a dark room.

Distance P (cm) (torch to object)	Distance Q (cm) (object to screen)	Shadow size
12	8	Small
10	10	Medium
6	14	Large

(a) State the relationship between the distance of the object from the torch and the size of the shadow. [2]

(b) Why must Ali keep the torch and screen at the same positions? [1]

Question 13

Sam conducted an experiment to find out how well four different materials — A, B, C and D — reflect light.

Material	Amount of light reflected (units)
A	30
B	70
C	50
D	120

(a) Which material is most suitable for making a safety vest for jogging at night? Explain your answer. [2]

(b) Sam painted the same material in four different colours and measured the reflected light. He found that white reflected the most light and black reflected the least. What can Sam conclude? [1]

Question 14

Sally set up an experiment in a dark room. She placed a sheet of material X between a torch and a light sensor. She repeated the experiment by increasing the number of sheets and recorded the results.

Number of sheets	Amount of light detected (units)
1	380
2	250
3	150
4	80

(a) State the relationship between the number of sheets of material X and the amount of light detected. [1]

(b) Based on the property of light, why did Sally place the light sensor and torch at the same height? [1]

Answer Key

Section A — Multiple Choice

Q1: C Q2: B Q3: A Q4: D Q5: A Q6: D Q7: A Q8: B Q9: C Q10: B

Section B — Structured Questions

Q11

(a) Object S (0 units of light passed through)

(b) R = translucent (allows some light); S = opaque (no light); T = translucent (allows some light); U = transparent (allows most/all light)

(c) To prevent extra light from entering and affecting the readings / To ensure a fair test

Q12

(a) The closer the object is to the torch, the larger the shadow. (OR The further the object is from the torch, the smaller the shadow.)

(b) To ensure a fair test / To keep the total distance constant

(c) The shadow size would become smaller (the object is further from the torch)

Q13

(a) Material D. It reflects the most light (120 units), making the wearer more visible at night.

(b) Lighter colours reflect more light than darker colours.

(c) To prevent extra light from entering and affecting the readings

Q14

(a) As the number of sheets increases, the amount of light detected decreases.

(b) Light travels in straight lines. Placing them at the same height ensures the light passes through the material and reaches the sensor.