Primary 5 Science Light Quiz

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Primary 5 Science Quiz - Light

Name: ________________________
Class: Primary 5 ______
Date: ________________________
Score: ______ / 40

Duration: 45 minutes
Total Marks: 40

Instructions:

1. Answer all questions.
2. Write your answers in the spaces provided.
3. For multiple-choice questions, write the letter (A, B, C, or D) in the bracket provided.
4. For open-ended questions, write your answers clearly in complete sentences.
5. Diagrams are not drawn to scale unless stated.

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Section A: Multiple-Choice Questions (10 × 1 mark = 10 marks)

1. Which of the following is a natural source of light?
A) Torch
B) Candle flame
C) The Sun
D) Light bulb

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2. Light travels in a __________.
A) curved line
B) straight line
C) zigzag line
D) circular path

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3. Which of the following objects is transparent?
A) Wooden door
B) Frosted glass
C) Clear glass window
D) Cardboard box

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4. When light hits a smooth, shiny surface like a mirror, it is __________.
A) absorbed
B) refracted
C) reflected
D) transmitted

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5. A shadow is formed when __________.
A) light passes through an object
B) an object blocks light
C) light bends around an object
D) an object produces its own light

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6. Which of the following will produce the sharpest shadow?
A) A large light source far from the object
B) A small light source close to the object
C) A large light source close to the object
D) A small light source far from the object

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7. The diagram below shows a light ray hitting a plane mirror.

Generated diagram for Q7.

If the angle of incidence is 30°, what is the angle of reflection?
A) 15°
B) 30°
C) 60°
D) 90°

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8. Which of the following statements about light is correct?
A) Light can travel through a vacuum.
B) Light travels faster in water than in air.
C) Light cannot travel through transparent objects.
D) Light travels in curved lines.

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9. Peter places a stick vertically in a beaker of water. When viewed from the side, the stick appears bent at the water surface. This is because light __________.
A) is reflected by the water
B) is absorbed by the water
C) changes direction when it passes from air into water
D) travels slower in air than in water

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10. Four objects are placed between a light source and a screen as shown below.

Generated diagram for Q10.

Which object will cast the largest shadow on the screen?
A) Object A
B) Object B
C) Object C
D) Object D

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Section B: Short Answer Questions (5 × 2 marks = 10 marks)

11. Classify the following objects into "Luminous" and "Non-luminous" by writing them in the correct column.
Objects: Firefly, Moon, Torch, Book, Sun, Mirror

Luminous	Non-luminous

12. The diagram below shows a ray of light passing from air into a glass block.

Generated diagram for Q12.

(a) Name the phenomenon that occurs when light passes from air into glass.

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(b) Does the light ray bend towards or away from the normal when it enters the glass block?

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13. A student shines a torch at a red apple in a dark room. The apple appears red. Explain why the apple appears red.

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14. The diagram below shows an object placed between a light source and a screen. A shadow is formed on the screen.

Generated diagram for Q14.

(a) State one property of light that allows a shadow to be formed.

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(b) If the object is moved closer to the light source, what will happen to the size of the shadow on the screen?

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15. Complete the table below by stating whether each material is transparent, translucent, or opaque.

Material	Classification (Transparent / Translucent / Opaque)
Clear plastic wrap
Aluminium foil
Tissue paper
Spectacle lens
Wooden chopstick

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Section C: Structured / Open-Ended Questions (5 × 4 marks = 20 marks)

16. The diagram below shows a periscope.

Generated diagram for Q16.

(a) On the diagram, draw the path of a light ray from the object to the observer's eye. Use a ruler and arrows to show the direction.

Generated diagram for this question.

(b) State the angle at which each mirror is positioned relative to the horizontal.

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(c) Explain why plane mirrors are used in a periscope instead of curved mirrors.

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(d) If the top mirror is rotated slightly so that it is no longer at 45°, what will the observer see?

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17. An experiment is set up to investigate how the distance between a light source and an object affects the size of the shadow formed on a screen. The screen is kept at a fixed distance from the object.

The results are shown in the table below.

Distance between light source and object (cm)	Height of shadow on screen (cm)
10	40
20	25
30	20
40	17
50	15

(a) State the relationship between the distance of the light source from the object and the size of the shadow.

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(b) Predict the height of the shadow when the distance between the light source and the object is 60 cm.

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(c) Explain why the shadow becomes smaller when the light source is moved further away from the object.

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(d) State one variable that must be kept constant to ensure a fair test.

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18. The diagram below shows a ray of white light passing through a triangular glass prism.

Image pending generation: diagram for Q18.

(a) What is the name of the phenomenon where white light splits into different colours?

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(b) List the seven colours of the spectrum in order from the least deviated to the most deviated.

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(c) Why does white light split into different colours when it passes through a prism?

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(d) If a red filter is placed in front of the white light source, what will be observed on the screen?

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19. Mei Ling wants to see over a tall fence without climbing it. She decides to make a simple device using two plane mirrors and a cardboard tube.

(a) Draw a labelled diagram to show how Mei Ling should arrange the two mirrors in the tube so that she can see over the fence.

Generated diagram for Q19.

(b) State the principle of reflection that allows this device to work.

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(c) If Mei Ling uses a concave mirror instead of a plane mirror at the top, how would the image appear different?

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(d) Suggest one improvement Mei Ling could make to see a clearer image.

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20. The diagram below shows an optical fibre. Light enters one end and travels through the fibre by undergoing multiple total internal reflections.

Generated diagram for Q20.

(a) What condition must be met for total internal reflection to occur at the core-cladding boundary?

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(b) State one advantage of using optical fibres over copper wires for transmitting information.

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(c) Explain why the cladding must have a lower refractive index than the core.

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(d) In medical endoscopes, optical fibres are used to see inside the body. State one property of light that makes this possible.

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End of Quiz

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Primary 5 Science Quiz - Light (Answer Key)

Total Marks: 40

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Section A: Multiple-Choice Questions (10 × 1 mark = 10 marks)

1. C – The Sun is a natural source of light. Torch, candle flame, and light bulb are artificial sources.
Mark: 1

2. B – Light travels in straight lines. This is a fundamental property of light.
Mark: 1

3. C – Clear glass window allows light to pass through completely so objects can be seen clearly through it. Wooden door and cardboard box are opaque; frosted glass is translucent.
Mark: 1

4. C – Reflection occurs when light bounces off a smooth, shiny surface like a mirror.
Mark: 1

5. B – A shadow is formed when an opaque or translucent object blocks light from reaching a surface.
Mark: 1

6. D – A small (point) light source far from the object produces the sharpest shadow because the light rays are nearly parallel. Large or close sources produce fuzzy shadows (umbra and penumbra).
Mark: 1

7. B – Law of reflection: Angle of incidence = Angle of reflection. If angle of incidence is 30°, angle of reflection is also 30°.
Mark: 1

8. A – Light can travel through a vacuum (e.g., sunlight reaching Earth). Light travels slower in water than in air; it travels through transparent objects; it travels in straight lines.
Mark: 1

9. C – This is refraction: light changes direction when it passes from one medium (air) into another (water) of different optical density.
Mark: 1

10. A – Object A is closest to the light source. The closer an object is to the light source, the larger the shadow cast on a fixed screen (due to greater divergence of light rays).
Mark: 1

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Section B: Short Answer Questions (5 × 2 marks = 10 marks)

11. (2 marks – ½ mark each correct classification)

Luminous	Non-luminous
Firefly	Moon
Torch	Book
Sun	Mirror

Marking notes:

• Luminous objects emit their own light.
• Moon and mirror only reflect light; they do not produce their own.
• Common mistake: Classifying Moon as luminous.

12. (2 marks)
(a) Refraction – The bending of light when it passes from one medium to another of different optical density.
Mark: 1

(b) Towards the normal – Light slows down when entering a denser medium (glass), causing it to bend towards the normal.
Mark: 1

13. (2 marks)
The white light from the torch contains all colours. The red apple absorbs most colours (orange, yellow, green, blue, indigo, violet) and reflects red light into our eyes.
Mark breakdown:

• Mention white light contains all colours / apple absorbs other colours: 1 mark
• Apple reflects red light to our eyes: 1 mark

Teaching note: Emphasise that colour of an object is the colour of light it reflects.

14. (2 marks)
(a) Light travels in straight lines. (Accept: Light cannot bend around the object / Light is blocked by opaque objects.)
Mark: 1

(b) The shadow will become larger. When the object moves closer to the light source, the light rays diverge more, casting a larger shadow on the fixed screen.
Mark: 1

15. (2 marks – ½ mark each)

Material	Classification
Clear plastic wrap	Transparent
Aluminium foil	Opaque
Tissue paper	Translucent
Spectacle lens	Transparent
Wooden chopstick	Opaque

Marking notes:

• Transparent: allows light to pass through, objects seen clearly.
• Translucent: allows some light to pass, objects not seen clearly.
• Opaque: does not allow light to pass through.

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Section C: Structured / Open-Ended Questions (5 × 4 marks = 20 marks)

16. (4 marks)
(a) Diagram: Light ray from object → strikes top mirror at 45° → reflects down tube (90° turn) → strikes bottom mirror at 45° → reflects horizontally to observer's eye. Arrows must show direction.
Mark: 1 (for correct path with arrows)

(b) 45° to the horizontal (or 45° to the vertical).
Mark: 1

(c) Plane mirrors produce upright, same-size, laterally inverted images without distortion. Curved mirrors would magnify, reduce, or distort the image, making it unsuitable for viewing objects at their true size and orientation.
Mark: 1

(d) The observer will not see the object / the image will be displaced / the light ray will not reach the observer's eye. The mirror must be at exactly 45° to turn the light ray by 90° down the tube.
Mark: 1

17. (4 marks)
(a) As the distance between the light source and the object increases, the height of the shadow decreases. (Inverse relationship)
Mark: 1

(b) Approximately 13–14 cm (accept 12–15 cm with valid reasoning). The shadow height decreases at a decreasing rate; extrapolating from the trend (40→25→20→17→15), the next drop is about 2–3 cm.
Mark: 1

(c) When the light source is further away, the light rays reaching the object are more parallel (less divergent). This causes the shadow to be smaller and sharper, closer to the actual size of the object.
Mark: 1

(d) Distance between object and screen (or: size of object, size of light source, brightness of light source, position of screen).
Mark: 1

18. (4 marks)
(a) Dispersion (or: Dispersion of light).
Mark: 1

(b) Red, Orange, Yellow, Green, Blue, Indigo, Violet (ROYGBIV).
Mark: 1 (all 7 in correct order)

(c) Different colours of light travel at different speeds in glass (different refractive indices). Violet light slows down the most and bends the most (shortest wavelength); red light slows down the least and bends the least (longest wavelength). This causes the colours to separate.
Mark: 1

(d) Only a red band/line will be seen on the screen. The red filter only allows red light to pass through; all other colours are absorbed. Since only red light enters the prism, no dispersion occurs.
Mark: 1

19. (4 marks)
(a) Diagram: Similar to periscope in Q16. Cardboard tube with two plane mirrors at 45° at each end. Light from object above fence → top mirror (45°) → reflects down tube → bottom mirror (45°) → reflects to eye. Labels: Top mirror, Bottom mirror, Cardboard tube, Object, Eye, Light ray path with arrows.
Mark: 1 (correct arrangement with labels)

(b) Angle of incidence = Angle of reflection (Law of reflection).
Mark: 1

(c) The image would appear magnified / larger / distorted. A concave mirror converges light rays, producing a magnified virtual image when the object is within the focal length.
Mark: 1

(d) Use a longer tube / ensure mirrors are perfectly flat and at exactly 45° / use higher quality mirrors with less absorption / paint inside of tube black to reduce internal reflections. (Any one valid improvement)
Mark: 1

20. (4 marks)
(a) The angle of incidence must be greater than the critical angle, and light must travel from a denser medium (core) to a less dense medium (cladding).
Mark: 1 (both conditions needed)

(b) Optical fibres can transmit data over longer distances with less signal loss / higher bandwidth / immune to electromagnetic interference / lighter and thinner. (Any one valid advantage)
Mark: 1

(c) For total internal reflection to occur, light must travel from a medium of higher refractive index (core) to a medium of lower refractive index (cladding). If the cladding had a higher or equal refractive index, light would refract into the cladding instead of reflecting back into the core.
Mark: 1

(d) Light travels in straight lines / Light can be reflected (total internal reflection) / Light can travel through transparent fibres. (Any one relevant property – most directly: Light can undergo total internal reflection to travel along curved paths.)
Mark: 1

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Total: 40 marks

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Common Mistakes to Watch For:

1. Q3, Q15: Confusing translucent and transparent. Transparent = see clearly; Translucent = see blurred/shadow only.
2. Q6, Q10, Q14, Q17: Shadow size relationships. Closer to light source = larger shadow. Further from light source = smaller shadow.
3. Q7, Q16: Law of reflection. Angle measured from normal, not from mirror surface.
4. Q9, Q12, Q18: Refraction vs Reflection. Refraction = bending when changing medium. Reflection = bouncing off surface.
5. Q13: Colour of object = colour reflected, not colour absorbed.
6. Q18: Order of spectrum (ROYGBIV) and which colour deviates most (violet) vs least (red).
7. Q20: Total internal reflection requires: (1) denser to less dense medium, (2) angle > critical angle.