periscope

A periscope is a tool that allows you to see things that you would not be able to see otherwise. It works by reflecting light through a system of mirrors.

Here's how it works:

• Light from an object strikes the top mirror in the periscope.
• The mirror reflects the light at a 45-degree angle.
• The light travels down the periscope tube.
• The bottom mirror reflects the light at a 45-degree angle.
• The light enters your eye and you can see the object.

Periscopes are often used by submarines to see above the water without having to surface. They are also used by firefighters to see through smoke and by soldiers to see over walls.

The submarine used a periscope to observe the surface of the water.