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Light: Shadows and Reflections

A hole makes a picture

A shadow keeps only an outline, the line round a shape. Yet a tiny hole can make a whole picture.

A box with a tiny hole faces an object outside.
Step 1 of 4
  1. A box with a tiny hole faces an object outside.
  2. Light from the top and the bottom crosses at the hole.
  3. The top lands low. The bottom lands high. It is upside down.
  4. Widen the hole, and the picture blurs (turns fuzzy).

The new words

  • Image — a picture made by light from the real thing.
  • Pinhole camera — a dark box with one tiny hole.

The rule

Light from the top of the object lands low on the screen. Light from the bottom lands high. So the picture flips upside down. A wider hole blurs the whole picture.

Light goes straight, so the rays cross at the hole.

Never point your box at the Sun. Point it at a street.

Now try it. Read each question. Tap the answer.

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This track

  1. 0 Start here
  2. 1 Light travels in straight lines
  3. 2 A shadow is a place light did not reach
  4. 3 How big, and what shape
  5. 4 A hole makes a picture
  6. 5 Light bounces off a smooth surface
  7. 6 What you see in a mirror
  8. 7 Why a wall shows you nothing
  9. 8 Checkpoint: straight lines, shadows and mirrors
  10. 9 Does it make its own light?
  11. 10 How much light gets through?
  12. 11 A simple periscope uses two mirrors
  13. 12 The big picture
  14. 13 Track quiz

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