Primary 4 · Science · Energy: Light & Shadows
Energy: Light & Shadows questions for Primary 4 Science
10 questions to work through online, 2 of them written out the way the paper asks. Answer and you get the working straight away, then a score at the end. No sign-up, and you can retake it as often as you like.
- What makes a shadow
- Transparent, translucent, opaque
- Changing shadow size
- Shape of a shadow
- Reading results
- Fair testing with light
- Translucent materials
- Naming a property
- How light travels
- Shadows outdoors
| Distance from torch to toy | Height of shadow (cm) |
|---|---|
| 10 cm | 36 |
| 20 cm | 22 |
| 30 cm | 17 |
| 40 cm | 14 |
Answers and explanations for all 10 questions
Every answer with the reasoning behind it. Worth reading after you have tried the set — or on its own, if you are a parent marking it.
A shadow forms behind an object because the object
Answer: blocks the light travelling towards it
Light travels in straight lines. Where an object blocks the light travelling towards it, none reaches the screen behind, and that dark patch is the shadow.
Which two of these objects would cast a dark, sharp-edged shadow?
Answer: A and C only
Only opaque objects block light completely. Wood and metal are opaque; clear glass is transparent and tracing paper is translucent, so both let light through.
In the set-up above, how could the shadow on the wall be made larger without moving the wall or changing the toy?
Answer: move the torch closer to the toy
The closer the light is to the object, the more the rays spread out past it before reaching the wall, so the shadow grows. Brightness changes how dark it is, not how big.
A cylinder is held with its flat circular end facing a lamp. What shape is its shadow on the screen behind?
Answer: a circle
A shadow takes the outline of the object as the light meets it. With the flat circular end facing the lamp, that outline is a circle.
Based on the table above, what is the relationship between the distance and the shadow?
Answer: The further the torch is from the toy, the smaller the shadow.
As the distance goes 10, 20, 30, 40 cm, the shadow falls 36, 22, 17, 14 cm. The further the torch, the smaller the shadow.
A pupil wants to test whether the distance of a lamp changes the size of a shadow. Which two things must stay the same?
Answer: A and C only
Only the lamp's distance changes. The object and the screen must stay put, or a difference in the shadow could have come from either of them instead.
Why is frosted glass used in a bathroom window rather than clear glass?
Answer: It lets light through but you cannot see clearly through it.
Frosted glass is translucent: light passes through so the room is lit, but the light is scattered so no clear image gets through.
A material lets no light through at all, so a sharp dark shadow forms behind it. What is such a material called?
Answer: opaque
A material that lets no light through is opaque.
Shadows have sharp edges that match the outline of the object. This is evidence that light travels in ______ lines.
Answer: straight
Sharp-edged shadows show that light travels in straight lines and cannot bend round the object.
Why is a person's shadow much longer in the late afternoon than at midday?
Answer: The sun is lower in the sky, so its light comes in at a slant.
At midday the sun is high and light comes down almost from above, giving a short shadow. Later the sun is low, so the light slants across and the shadow stretches out.