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Primary 6 PSLE Science Light Quiz
Free P6 PSLE Science Light quiz, LongCat Exam version, with questions, answers, and PSLE-focused practice for Singapore students.
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Primary 6 PSLE Science Quiz - Light
Answer Key
Section A: Multiple Choice Questions (10 × 1 mark = 10 marks)
1. C — straight
Light travels in a straight line (rectilinear propagation).
2. D — The Sun
The Sun is a natural source of light. A candle flame and a torch are artificial sources. The Moon only reflects light from the Sun and does not produce its own light.
3. B — reflected
When light hits a smooth, shiny surface, it bounces off (reflection).
4. B — light travels in a straight line and cannot pass through the object
Shadows are formed because light travels in straight lines and opaque objects block the light.
5. C — dispersed
A rainbow is formed when white light is dispersed (split into its component colours) by water droplets.
6. D — Red
In the visible spectrum, red has the longest wavelength (~700 nm) and violet has the shortest (~400 nm).
7. C — refracted
Different colours of light are refracted by different amounts when passing through a prism, causing dispersion.
8. D — inverted and diminished
A pinhole camera forms a real, inverted image. The size depends on the distances involved but is typically diminished.
9. C — Clear glass
Clear glass is transparent and allows most light to pass through. Wooden board and brick wall are opaque; frosted glass is translucent.
10. B — noon
At noon, the Sun is at its highest point in the sky, so the shadow cast is the shortest.
Section B: Short-Answer Questions (20 marks)
11. [2 marks] (a) Light travels in a straight line. [1] (b) Light can be reflected / refracted / dispersed / absorbed. [1]
Accept any two valid properties of light.
12. [2 marks] (a) Angle of incidence = 90° − 35° = 55° [1]
The angle of incidence is measured from the normal, not the mirror surface.
(b) Angle of reflection = 55° [1]
By the law of reflection, angle of incidence = angle of reflection.
13. [2 marks] (a) Refraction [1]
(b) Light travels at different speeds in water and air. When light passes from water to air, it changes speed and bends, causing the pencil to appear bent at the water surface. [1]
Key point: change in speed of light in different media causes bending.
14. [2 marks] (a) Pinhole camera [1]
(b) The image is inverted (upside down) / real / diminished [1]
Accept any one valid characteristic.
15. [2 marks] The sky appears blue because of scattering of sunlight by gas molecules in the atmosphere. [1] Blue light has a shorter wavelength and is scattered more than other colours, so the sky appears blue. [1]
Must mention scattering and the reason (shorter wavelength scattered more).
16. [2 marks] Colour: Red [1]
Explanation: A white object reflects all colours of light. When illuminated with only red light, only red light is available to be reflected, so the object appears red. [1]
Key concept: the colour of an object depends on the colour of light illuminating it and the colour it reflects.
17. [3 marks] (a) Dispersion [1]
(b) Violet [1]
Violet light has the shortest wavelength and is refracted the most.
(c) Formation of a rainbow [1]
Accept any valid natural phenomenon involving dispersion of white light.
18. [2 marks] (a) The shadow should be drawn on the ground on the side of the person opposite to the lamp post. The shadow should be a dark region directly behind the person (relative to the light source). [1]
Award mark for correct position and reasonable shape of the shadow.
(b) The shadow is formed because light travels in a straight line and cannot pass through the opaque person, so a dark region (shadow) is formed behind the person. [1]
Must mention: light travels in straight lines + object is opaque/blocks light.
Section C: Structured / Application Questions (10 marks)
19. [5 marks] (a) To investigate how the distance of the card (pinhole) from the light source affects the size of the light spot (image) on the screen. [1]
Accept any clearly stated aim related to the variables in the experiment.
(b) The distance of the card from the light source (or the position of the card). [1]
(c) Observation: The light spot on the screen will be larger when the card is closer to the light source (Card A) and smaller when the card is farther from the light source (Card C). [1]
Explanation: When the pinhole is closer to the light source, the cone of light passing through the hole spreads out more before reaching the screen, producing a larger spot. When the pinhole is farther from the light source, the light is more focused, producing a smaller spot. [1]
Accept equivalent explanations based on the geometry of light rays passing through the pinhole.
(d) The size of the hole / the distance between the last card and the screen / the brightness of the light source [1]
Accept any one reasonable constant variable.
20. [5 marks] (a) 300,000,000 m/s (or 3 × 10⁸ m/s) [1]
(b) Working: Distance = Speed × Time [1] Distance = 340 m/s × 6 s = 2,040 m [1]
Award 1 mark for correct formula and 1 mark for correct answer with unit.
(c) Lightning and thunder occur at the same time and place. We see the lightning first because light travels much faster than sound, so the light reaches our eyes before the sound reaches our ears. [1]
Key point: simultaneous events; difference in arrival time is due to different speeds.
(d) Seeing a distant firework explosion before hearing the sound / seeing a person hammering a nail from far away before hearing the sound / seeing a cricket bat hit a ball before hearing the sound [1]
Accept any valid everyday example where light is observed before sound is heard.
Total: 40 marks