11. Answer in detail - III

1. Explain the working of a periscope.

 

A Periscopeis an instrument used to observe over, around  or through an object, obstacle or environmental condition that prevents indirect line-of-sight observationdirect line-of-sight observation from an observer's current position.

Hippolyte Marie-DavyKayvon BeykpourIsaac NewtonSimon Lake invented the first naval periscope in 1884192219021854, which contains a vertical tube with two small mirrors fixed at each end at 30°60°45°90°. Simon LakeKayvon BeykpourHippolyte Marie-DavyIsaac Newton used periscopes in his submarines in 1902185419221884.

 

It is an instrument used for observing bodies or ships, which are over and around another body or a submarine.

It works on the principle of the law of diffractionlaw of dispersionlaw of refraction of lightlaw of reflection of light. It contains a long outer case, and inside this case, mirrors or prisms are placed at each end with an inclination angle of 90°45°60°30°.

Light coming from the distant body strikes the mirror at the top end of the periscope, and it gets reflected vertically downwardhorizontallyvertically upward. This light is reflected again by the next mirror placed at the bottom to move vertically downwardvertically upwardhorizontally and reach the observer's eye.