Educator Features

Construct a Periscope

The student will experiment with a simple periscope to see how it reflects light.

Science and Mathematics Standards

Science Standards:
  • Physical Science

  • Mathematics Standards:
  • Communication

  • Connection

  • Computation/Estimation

  • Measurement

  • Theory

    A periscope is an optical instrument that uses a system of prisms, lenses, or mirrors to reflect images through a tube. Light from a distant object strikes the top mirror and is then reflected at an angle of 90 degrees down the periscope tube. At the bottom of the periscope, the light strikes another mirror and is then reflected into the viewer's eye. This simple periscope uses only flat mirrors as compared to the periscopes used on submarines, which are usually a complex optical system using both lenses and mirrors.

    • 2 flat mirrors

    • a cardboard tube with openings on each end

    • wooden supports

    • tape


    Insert both flat mirrors into the periscope viewing tube as shown. The mirrors must be facing each other. When the mirrors are inserted correctly each mirror will be resting on the wooden supports. As each mirror is inserted, place a small piece of Scotch tape over the mirror slots on the outside of the viewing tube. Hold the periscope so the mirrors are resting on the wooden supports, then look through it.
    NOTE: The mirrors will fall out if you turn your periscope upside down.

    diagram of how to make a periscope
    Periscope assembly illustration
    diagram of a periscope

    Observations, Data, and Conclusions

      1. Draw a diagram of the path a ray of light follows as it travels from an object, through the periscope, and into your eye.

      2. Do you think the periscope would work if the mirrors were at some angle other than 45 degrees?
    Optics: Light, Color and Their Uses Guide
    + View guide

    Excerpt from the Optics: Light, Color and Their Uses Guide