Question

what is periscope and what is its use?
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Answer 1

Answer:

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 current position. In its simplest form, it consists of an outer case with mirrors at each end set parallel to each other at a 45° angle.

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Answer 2

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Plane mirror is used in periscope. Each are placed at 45 degree.