Build a Periscope


What You Need:
  • Square mirrors - 2 small
  • A piece of strong cardboard - 30 x 30cms
  • Sticky tape
  • Ruler
  • Protractor
  • Scissors
  • Draw 3 vertical lines on the cardboard to divide it into 4 equal strips.
  • Cut squares in 2 of the strips as shown in the image.
  • Draw and cut 2 lines on each of the other 2 strips such that they make an angle of 45 degrees with the side of the card.
  • Fold the card into a tube and stick it together with tape.
  • Slide the mirrors into the angled slits and tape them in position. One mirror should face upwards and the other should face downwards.
  • If you hold the periscope sideways, you will be able to see around corners. If you hold it upright, you will be able to see over the heads of people or things that are taller than you are.

A periscope uses two mirrors that bounce reflections between them so people can see around corners or look at things that are too high for them to see. Light from the objects that are out of sight is reflected from the top mirror down into the lower mirror. You are able to see the objects by looking in the lower mirror.