RRB RPF RPSF SI and CONS Model Papers 6 with solutions

(1) A man in a submarine can see objects on the surface of sea with the help of a Periscope. A periscope is an instrument for observing over, around or through an object, obstacle or condition that prevents a direct line-of-sight observation from an observer's current position.
The simple form of a periscope consists of an outer case with mirrors at each end set parallel to each other at a 45° angle. Complex Periscopes use advanced prisms and fibre systems.