Unveiling the science behind periscopes

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What is Periscope?

A periscope is an optical instrument which is used to see objects that are not in the direct line of sight of observer. It is commonly used in such areas or places where the viewer is hidden or protected such as in submarines to observe surface above water.

Working Principle

Periscope works on the principle of reflection of light. When the light enters through one end of the hollow tube, it gets reflected from the mirror-1 (as shown in below picture). After the light is reflected from mirror-1, it then hits onto mirror-2 and where it is again reflected. Both mirrors are usually placed at 450 angle.

The light finally leaves the periscope after reflection from mirror-2. When the observer observes this reflected light, he sees the view that is in the line of sight of upper end of periscope. 

It explains the working principle of periscope. When the light reflected from an apple and enters the periscope, it is reflected off the first mirror. The first mirror is placed in 45 degree angle so that the light reflected off from the first mirror will then hit onto the second mirror which we will again reflect the light so that observer at the lower end can see the apple which is not placed in observer line of sight.

Application of Periscopes

  • Periscopes are used in submarines to observe the surface of the water while remaining submerged.
  • They are also used in tanks to help soldiers to see outside environment while staying protected.
  • It is also used in observation towers for security and surveillance purposes.
  • It is used in science experiment to help students to learn about the reflection of lights.

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