Primary 6 · Science · Energy: Light & Shadows
Energy: Light & Shadows questions for Primary 6 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.
- Shadow geometry
- Predicting from data
- What makes a shadow larger
- Why we see objects
- Transparent, translucent, opaque
- Reflection in use
- Naming a property
- Naming the evidence
- Applying the ideas
| Distance from lamp to card (cm) | Height of shadow (cm) |
|---|---|
| 10 | 60 |
| 20 | 30 |
| 30 | 20 |
| 40 | 15 |
| Material | Light passing through | Can you see clearly through it? |
|---|---|---|
| J | almost all | yes |
| K | about half | no |
| L | none | no |
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.
In the set-up above, which change would make the shadow on the screen smaller?
Answer: moving the lamp further from the card
The further the lamp, the closer its rays are to parallel by the time they pass the card, so the shadow is closer to the card's own size.
Based on the table above, what would the shadow height be at 60 cm?
Answer: 10 cm
Distance times height is 600 every time: 10 × 60, 20 × 30, 30 × 20, 40 × 15. At 60 cm the height is 600 ÷ 60 = 10 cm.
Which two changes would make a shadow larger?
Answer: A and B only
Size is geometry: how far the light is from the object and how far the screen is beyond it. Brightness and transparency affect only the darkness.
Why can a black cat be seen in a lit room but not in a completely dark one?
Answer: In the light some light bounces off it into your eyes; in the dark there is none to bounce.
Seeing requires light to travel from the object to the eye. A black surface reflects little, but in a lit room it reflects enough; in darkness there is nothing to reflect.
Based on the table above, which material would cast the darkest shadow?
Answer: L
The darkest shadow comes from the material that blocks the most light. L lets none through, which makes it opaque.
Which two of these depend on light being reflected?
Answer: A and B only
A mirror and a road sign both send light back to the viewer. A bulb is a source, and a warm pavement has absorbed the light rather than bouncing it.
Frosted bathroom glass lets light through but you cannot see clearly through it. Such a material is described as ______ .
Answer: translucent
A material that lets light through but scatters it so no clear image forms is translucent.
A shadow has a sharp edge that matches the outline of the object exactly. This is evidence that light travels in ______ lines.
Answer: straight
Sharp-edged shadows show that light travels in straight lines.
During a solar eclipse, the moon casts a shadow on the Earth. What does this tell you about the moon?
Answer: It is opaque, so it blocks the sunlight completely.
A shadow forms only where something blocks the light. The moon blocks it completely, which is exactly what being opaque means.