Shadow Shapes


You will need

  • torch
  • comb
  • clothes peg
  • sheet of white paper

What to do

It is best to do this activity in a darkened room.

Torch next to and away from comb

On a sheet of white paper, stand a comb upright using a peg as shown. Hold a torch close to the comb. Can you see the line shadows made by the comb?

Now move the torch away from the comb. What happens to the line shadows?

If you would like to keep a record of your experiment, use a pencil to trace the line shadows on the paper. Compare the traces for the torch close to and away from the comb.

Try this activity using sunlight instead of a torch. What pattern of shadow lines can you make using sunlight?

Think about it

Light rays travel in straight lines from the light source — the torch bulb. Light rays travel away from the bulb in all directions. When the comb is close to the bulb, light rays angle outwards in the shape of a fan as they pass through the comb. Therefore the shadow lines also fan outwards. As the torch moves further away from the comb, the angles between the shadow lines become smaller — they become almost parallel.

Shadow lines produced by the Sun (150 million kilometres away) always appear to be parallel.

Explore more

Have you noticed how the shape of the shadow on the moon changes? Can you design and make a model to show the phases of the moon — new, quarter, half and full Moon?

Design and make a model to show how a solar eclipse and a lunar eclipse form.

Become a portrait artist! Invite a friend to sit in front of a bright light to form a side-view face shadow on a wall. Place paper on the wall and trace the outline of the shadow.

Design and make shadow puppets with moving parts.