Primary 5 · Science · Energy: Light & Shadows
Energy: Light & Shadows questions for Primary 5 Science
9 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.
- Why we see things
- Shadow size
- Good reflectors
- Reading results
- Reflection in use
- What changes a shadow
- Naming what happens
- Naming a source
- Applying the ideas
| Distance from lamp to object (cm) | Height of shadow (cm) |
|---|---|
| 10 | 48 |
| 20 | 26 |
| 30 | 19 |
| 40 | 16 |
Answers and explanations for all 9 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.
Why can you not see a red book in a completely dark room?
Answer: There is no light to bounce off the book into your eyes.
We see an object when light bounces off it and enters the eye. With no light in the room, nothing reaches the eye and nothing is seen.
In the set-up above, the screen is moved further from the toy. What happens to the shadow?
Answer: It becomes larger.
Light spreads out from the lamp, so the shadow's edges keep diverging. Moving the screen back catches them further apart, giving a bigger shadow.
Which two surfaces reflect light best?
Answer: A and B only
Smooth, pale, shiny surfaces reflect best. Dark rough surfaces absorb the light instead, which is why they look black.
Based on the table above, which statement is correct?
Answer: Moving the lamp away makes the shadow smaller, but by less each time.
The shadow drops 22 cm, then 7 cm, then 3 cm. Each move of the lamp matters less than the one before.
Why does a cyclist wear a strip of shiny reflective material at night?
Answer: It sends car headlight beams back towards the driver.
The strip bounces headlight beams straight back towards their source, so the driver sees a bright patch where the cyclist is.
Which two changes would make a shadow on a screen larger?
Answer: A and B only
Size depends on geometry: how far the light is from the object and how far the screen is beyond it. Brightness and transparency change how dark the shadow is instead.
Light hits a mirror and bounces off it in a new direction. What is this called?
Answer: reflection
Light bouncing off a surface is reflection.
The sun, a candle and a lit bulb all make their own light. Such an object is called a light ______ .
Answer: source
An object that makes its own light is a light source.
The moon is not a light source, yet it is one of the brightest things in the night sky. How?
Answer: It reflects sunlight towards the Earth.
Sunlight falls on the moon and bounces off towards us. That is also why we see only the lit part, which changes shape through the month.