The Periscope was a very important instrument that was majorly used in World War - 1

A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's position

This is a simplistic application of a periscope. We will learn the working in detail, later in this story

The design of the periscope was invented with the basic objective of viewing objects without coming in the direct line of sight of the object

This is how an actual periscope looks like. Under the sea, it is mainly used by submarines to view nearby ships

It saw major use in World War-1, when periscopes were used to view enemy positions from trenches as shown

This is an example of a periscope rifle where soldiers used periscopes to fire at enemies without being seen

We shall try to understand the basic geometry and working principle of the periscope

It is a long S-Shaped cardboard hollow tube, which is bent twice in the middle

At each of the corner, there is a mirror placed at 45° with both the horizontal and the vertical

Light rays from infinity enter the periscope and hit the first mirror.

Following the Law of Reflection, the Reflected Ray gets reflected at an angle of 45° and goes vertically down

The Reflected Ray again hits the second mirror and gets reflected at an angle of 45° by the Laws of Reflection

After the second reflection, the light rays finally enter the eyes of the observer and he can see the object

This shows the elementary ray diagram of light rays, as they travel in a periscope

The above diagram shows how a submarine uses a periscope to view a ship

It is very simple to create a hands-on periscope at our homes

For that, we just need some cardboards and 2 plane mirrors

We cut the cardboard into an S-Shaped hollow tube and in the two corners, we place the mirrors

It must be remembered that the plane mirrors must be placed at an angle of 45° with the horizontal and vertical


A periscope is a device that helps us to see objects that are at a level higher than our eye level

It is a S-Shaped cardboard hollow tube bent at 2 corners. The corners include 2 plane mirrors at angle of 45°. The light rays get reflected at the two mirrors and finally reach the observer

The periscope finds extensive use in naval and military purposes

The End