From Real Exams Quiz
Primary 4 Science Light Quiz
Free P4 Science Light quiz, Nemo3 Exam version, with questions, answers, and syllabus-aligned practice for Singapore students.
These static practice materials are generated from the site's syllabus and paper-generation workflow, with source and model context shown so students and parents can evaluate the material before use.
Questions
Primary 4 Science Quiz - Light
Name: ___________________________
Class: Primary 4 _______
Date: ___________________________
Score: _______ / 40
Duration: 45 minutes
Total Marks: 40
Instructions:
- Answer all questions.
- For Section A, choose the correct answer and write its number (1, 2, 3 or 4) in the brackets provided.
- For Section B and C, write your answers in the spaces provided.
- The number of marks for each question is shown in brackets [ ] at the end of each question.
Section A: Multiple-Choice Questions (10 × 1 mark = 10 marks)
For each question, four options are given. Choose the correct answer and write its number (1, 2, 3 or 4) in the brackets provided.
1. Which of the following is a source of light?
(1) Moon
(2) Mirror
(3) Sun
(4) White paper
[ ]
2. Light travels in a __________.
(1) curved line
(2) straight line
(3) zigzag line
(4) circular path
[ ]
3. A shadow is formed when __________.
(1) light passes through an object
(2) light is reflected by an object
(3) an opaque object blocks light
(4) a transparent object allows light to pass through
[ ]
4. Which of the following materials is transparent?
(1) Wood
(2) Clear glass
(3) Cardboard
(4) Aluminium foil
[ ]
5. The diagram below shows a torch shining on a ball. A shadow is formed on the screen.
Generated diagram for Q5.
Which of the following statements about the shadow is correct?
(1) The shadow is smaller than the ball.
(2) The shadow is the same size as the ball.
(3) The shadow is larger than the ball.
(4) No shadow is formed because the ball is round.
[ ]
6. Four objects made of different materials are placed in the path of a beam of light. The table below shows the amount of light that passes through each object.
| Object | Material | Amount of light passing through |
|---|---|---|
| A | Clear plastic | Most |
| B | Frosted glass | Some |
| C | Wood | None |
| D | Tracing paper | Some |
Which two objects allow some light to pass through but you cannot see clearly through them?
(1) A and B
(2) B and D
(3) A and C
(4) C and D
[ ]
7. Peter stands between a lamp and a wall. His shadow is cast on the wall. What happens to the size of his shadow if he moves closer to the lamp?
(1) The shadow becomes smaller.
(2) The shadow becomes larger.
(3) The shadow remains the same size.
(4) The shadow disappears.
[ ]
8. Which of the following explains why we can see a book on the table?
(1) The book gives out its own light.
(2) Light from the surroundings is reflected by the book into our eyes.
(3) Light passes through the book into our eyes.
(4) Our eyes send out light to the book.
[ ]
9. The diagram below shows a light ray hitting a plane mirror.
Generated diagram for Q9.
If the angle of incidence is 30°, what is the angle of reflection?
(1) 15°
(2) 30°
(3) 60°
(4) 90°
[ ]
10. Which of the following objects will not form a shadow when light shines on it?
(1) A clear glass cup
(2) A metal spoon
(3) A wooden block
(4) A ceramic mug
[ ]
Section B: Structured Questions (6 × 2 marks = 12 marks)
Write your answers in the spaces provided.
11. The diagram below shows three objects A, B and C placed between a torch and a screen.
Generated diagram for Q11.
(a) Which object (A, B or C) will form the largest shadow on the screen? [1]
Answer: ___________________________
(b) Explain your answer in (a). [1]
12. Classify the following materials into the correct columns in the table below.
| Transparent | Translucent | Opaque |
|---|---|---|
Materials: Clear glass, Frosted glass, Wood, Tracing paper, Aluminium foil, Clean water [2]
13. The diagram below shows a light ray travelling from a torch, hitting a mirror, and reflecting into a boy's eye.
Generated diagram for Q13.
(a) On the diagram, label the angle of incidence and angle of reflection. [1]
(Labelled on diagram)
(b) State the law of reflection. [1]
14. Mei Ling wants to investigate how the distance between an object and the screen affects the size of the shadow. She sets up the experiment as shown below.
Image pending generation: experimental_setup for Q14.
(a) What is the independent variable (changed variable) in this experiment? [1]
(b) What is the dependent variable (measured variable) in this experiment? [1]
15. The diagram below shows a pencil placed in a beaker of water.
Generated diagram for Q15.
(a) The pencil appears bent at the water surface. This is because light __________ when it passes from water to air. [1]
(1) travels in a straight line
(2) is blocked
(3) bends
(4) is reflected
Answer: (____)
(b) What is this bending of light called? [1]
16. Ahmad shines a torch at a red apple in a dark room. The apple appears red.
(a) What colour of light is reflected by the red apple into Ahmad's eyes? [1]
(b) What happens to the other colours of light (e.g. blue, green) that hit the apple? [1]
Section C: Open-Ended Questions (3 × 6 marks = 18 marks)
Write your answers in the spaces provided.
17. Siti sets up an experiment to compare the size of shadows formed by three different objects (X, Y, Z) made of different materials. She uses the same torch and screen for all three objects. The objects are placed at the same distance from the torch. The diagram shows the shadows formed on the screen.
Generated diagram for Q17.
(a) Based on the shadows formed, classify objects X, Y and Z as opaque, translucent or transparent. [3]
Object X: ___________________________
Object Y: ___________________________
Object Z: ___________________________
(b) Explain why Object Y forms a faint and blurry shadow. [2]
(c) Siti wants to make the shadow of Object X smaller without moving the torch or the screen. What should she do? [1]
18. The diagram below shows a periscope made using two plane mirrors fixed at 45° in a long tube.
Generated diagram for Q18.
(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. [2]
(Drawn on diagram)
(b) Explain how the periscope allows the observer to see an object that is blocked by a wall. [2]
(c) If the top mirror is changed to a convex mirror, how would the image seen by the observer be different? [2]
19. Raj wants to find out how the distance between the torch and the object affects the size of the shadow. He keeps the screen at a fixed position. The table below shows his results.
| Distance between torch and object (cm) | Height of shadow on screen (cm) |
|---|---|
| 10 | 20 |
| 15 | 15 |
| 20 | 12 |
| 25 | 10 |
| 30 | 8 |
(a) State the relationship between the distance between the torch and the object and the height of the shadow. [1]
(b) Predict the height of the shadow if the distance between the torch and the object is 35 cm. [1]
(c) Explain why the shadow becomes smaller when the torch is moved further away from the object. [2]
(d) Raj repeats the experiment using a larger object (same shape, bigger size). How would the shadow heights in the table change? [2]
20. The diagram below shows a ray of light passing through a rectangular glass block.
Generated diagram for Q20.
(a) What happens to the light ray when it enters the glass block from air? [1]
(b) The light ray bends at the first surface. Why does it bend? [1]
(c) Compare the direction of the incident ray and the emergent ray. [1]
(d) If the glass block is replaced with a water tank (same rectangular shape), how would the bending of light at the first surface be different? [1]
(e) The speed of light in air is 300,000 km/s. In glass, light travels slower. State whether the speed of light in water is faster than, slower than, or the same as the speed of light in glass. [1]
(f) Why is the emergent ray laterally displaced (shifted sideways) from the incident ray? [1]
End of Quiz
Answers
Primary 4 Science Quiz - Light (Answer Key)
Total Marks: 40
Section A: Multiple-Choice Questions (10 × 1 mark = 10 marks)
1. Answer: (3) Sun
Explanation: The Sun is a natural light source that produces its own light. The Moon and mirrors only reflect light; white paper reflects light but does not produce it.
2. Answer: (2) straight line
Explanation: Light travels in straight lines. This is a fundamental property of light and explains why shadows have sharp edges when formed by a point source.
3. Answer: (3) an opaque object blocks light
Explanation: A shadow is a dark area formed when an opaque object blocks light from a source. Transparent objects allow light to pass through, so they do not form shadows.
4. Answer: (2) Clear glass
Explanation: Transparent materials allow almost all light to pass through so objects can be seen clearly through them. Wood and aluminium foil are opaque; clear glass is transparent.
5. Answer: (3) The shadow is larger than the ball.
Explanation: Because light rays diverge (spread out) from the torch, the shadow on the screen is magnified. The closer the object is to the light source, the larger the shadow. In the diagram, the ball is closer to the torch than to the screen, so the shadow is larger than the ball.
6. Answer: (2) B and D
Explanation: Frosted glass and tracing paper are translucent — they allow some light to pass through but scatter it, so you cannot see clearly through them. Clear plastic (A) is transparent; wood (C) is opaque.
7. Answer: (2) The shadow becomes larger.
Explanation: When an object moves closer to the light source, it blocks more of the diverging light rays, casting a larger shadow on the wall. This is the same principle as in Q5.
8. Answer: (2) Light from the surroundings is reflected by the book into our eyes.
Explanation: Most objects (like books) are non-luminous — they do not produce light. We see them because light from a source (e.g., room lights, sunlight) hits them and reflects into our eyes.
9. Answer: (2) 30°
Explanation: Law of reflection: Angle of incidence = Angle of reflection. If the angle of incidence is 30°, the angle of reflection is also 30°.
10. Answer: (1) A clear glass cup
Explanation: A clear glass cup is transparent — it allows light to pass through, so it does not block light to form a shadow. The other objects (metal spoon, wooden block, ceramic mug) are opaque and will form shadows.
Section B: Structured Questions (6 × 2 marks = 12 marks)
11.
(a) Object A [1]
(b) Object A is closest to the torch. Light rays diverge from the torch, so the object nearest to the light source blocks a wider spread of rays, forming a larger shadow on the screen. [1]
Marking note: Must mention "closest to torch" and "diverging rays" or "blocks more light" for full mark.
12. [2 marks total; ½ mark per correct placement]
| Transparent | Translucent | Opaque |
|---|---|---|
| Clear glass, Clean water | Frosted glass, Tracing paper | Wood, Aluminium foil |
Common mistake: Placing "clean water" as translucent. Water is transparent.
13.
(a) Angle of incidence (i) labelled between incident ray and normal; Angle of reflection (r) labelled between reflected ray and normal. Both angles equal (40°). [1]
(b) The angle of incidence is equal to the angle of reflection. [1]
Alternative acceptable: "The incident ray, reflected ray, and normal all lie in the same plane." But the angle equality is the key P4 concept.
14.
(a) Distance between the card (object) and the screen. [1]
(b) Size (height/area) of the shadow on the screen. [1]
Marking note: "Size of shadow" alone is acceptable; "height of shadow" is more precise.
15.
(a) (3) bends [1]
(b) Refraction [1]
Explanation: Light changes speed when it passes from one medium (water) to another (air) of different optical density, causing it to bend. This bending is called refraction.
16.
(a) Red light [1]
(b) The other colours (blue, green, etc.) are absorbed by the apple. [1]
Explanation: A red apple appears red because it reflects red light and absorbs most other colours of the visible spectrum.
Section C: Open-Ended Questions (3 × 6 marks = 18 marks)
17.
(a) Object X: Opaque [1]
Object Y: Translucent [1]
Object Z: Transparent [1]
Reasoning: Opaque objects block all light → sharp dark shadow. Translucent objects allow some light through but scatter it → faint blurry shadow. Transparent objects allow most light through → no shadow.
(b) Object Y is translucent. It allows some light to pass through but scatters the light in different directions, so only a small amount of light reaches the screen, forming a faint shadow. The scattering also makes the edges blurry. [2]
Mark breakdown: 1 mark for "translucent / allows some light through", 1 mark for "scatters light / blurry edges".
(c) Move Object X closer to the screen (or further from the torch). [1]
Explanation: Moving the object away from the light source (towards the screen) reduces the spread of blocked rays, making the shadow smaller.
18.
(a) Light ray drawn from object → top mirror (45° incidence) → reflects 90° down tube → bottom mirror (45° incidence) → reflects 90° horizontally to eye. Arrows show direction. [2]
Mark breakdown: 1 mark for correct path with 90° turns at each mirror, 1 mark for arrows showing direction from object to eye.
(b) Light from the object hits the top mirror, reflects down the tube to the bottom mirror, then reflects horizontally to the observer's eye. This allows the observer to see over the wall because the light path is bent by the mirrors. [2]
Mark breakdown: 1 mark for describing the two reflections, 1 mark for explaining how it sees over the wall (light path bent).
(c) The image would appear smaller and upright (virtual), and the field of view would be wider. A convex mirror diverges light rays, producing a diminished image. [2]
Mark breakdown: 1 mark for "smaller/diminished", 1 mark for "wider field of view" or "upright virtual image". At P4 level, "smaller and wider view" is sufficient.
19.
(a) As the distance between the torch and the object increases, the height of the shadow decreases. [1]
Or: "The further the torch from the object, the smaller the shadow."
(b) 6 cm (or approximately 6–7 cm) [1]
Reasoning: The pattern shows shadow height decreasing by 5, 3, 2, 2 cm. The decrease is slowing. Extrapolating: 8 cm → ~6 cm. Accept 6–7 cm with valid reasoning.
(c) When the torch is further from the object, the light rays reaching the object are more parallel (less divergent). The object blocks a narrower beam of light, so the shadow cast on the fixed screen is smaller. [2]
Mark breakdown: 1 mark for "rays more parallel / less divergent", 1 mark for "blocks narrower beam / smaller shadow".
(d) All shadow heights in the table would be larger (greater) because a larger object blocks more light, casting a bigger shadow at each distance. [2]
Mark breakdown: 1 mark for "larger shadows", 1 mark for "blocks more light / bigger object".
20.
(a) The light ray bends towards the normal. [1]
(b) Light slows down when it enters the denser medium (glass) from air, causing it to change direction (refract). [1]
Key concept: Change in speed → change in direction.
(c) The emergent ray is parallel to the incident ray but laterally displaced (shifted sideways). [1]
(d) The bending would be less (smaller angle of refraction) because water is less optically dense than glass, so light slows down less in water than in glass. [1]
At P4 level: "Less bending in water" is acceptable.
(e) Faster than [1]
Explanation: Light travels faster in water than in glass because water has a lower refractive index (less optically dense).
(f) The ray bends towards the normal when entering the glass, travels straight through, then bends away from the normal when exiting. The two bends are in opposite directions but the parallel faces cause the emergent ray to be parallel to the incident ray, shifted sideways. [1]
Key point: Parallel faces of the block cause the two refractions to cancel in direction but not in position.
End of Answer Key
Free quiz and exam paper access
Enter your details to view this paper
Your access is remembered on this device.