what is a periscope?

Answer 1

Refer to the link given below.

Answer 2

It is an optical instrument that passes light through a system of mirrors and prisms that permit the user to view an image at a height or lower than their eye, its most common use to allow a submariner to view ships on the surface while the submarine is at periscope depth.

Answer 3

A periscope is an optical device which lets you see (by the use of mirrors) around corners, or up and over some obstruction.

In tanks, periscopes were used to let tank operators see up and over the armor plate of their tank.

In WW 1 periscopes were used to let men in trenches see out over the top of the trench without getting themselves shot.

In WW II periscopes were used in submarines by all countries to allow men in the submarine down below the water's surface to see things above the surface.

In general one lools into a tilted mirror which looks at another tilted mirror that provides the view. In practice, the mirror that provides the view could be adjusted in angle somewhat to allow the viewer to look up, straight ahead, or somewhat downward just by varying the angle of the mirror somewhat.

construction of a simple periscope requires only two mirrors and some form of tube or long box to mount them in. The actual size of the tube or box depends upon the mirrors that are available. Place a viewing hole in one end of the box, and the first mirror at a 45 degree angle inside the viewing hole. Some kind of glue or tape will be needed to hold the mirror in that position.

Next cut out a seeing hole at the other end of the box and install the second mirror such that the first mirror can see it, and so that that mirror looks out of the box through the hole you just cut.

This might sound rather complex, but in practice, it is quite simple if you think of the path of the light rays coming "into" the periscope as hitting the first mirror to bounce off at a 90 degree angle, and down to the second mirror at the other end of the box (or tube) below, and bounce off of that one at another 90 degree angle into your eye.

If you set the mirrors up one way, you can see over your head and behind you, and set up the other way, you can see over your head and in front of you. Turn the periscope on its side and you could look around a corner without exposing yourself. etc., etc.