Q. The mirror used in search light is –

Explanation by: Gopal Sharma

A search light produces an intense parallel beam of 
light. This requires a reflector of large aperture. When 
a source is placed at the focus of a large concave 
mirror only the paraxial rays (not the marginal rays) are 
reflected as parallel beam, but when a source is placed 
at the focus of parabolic mirror all the rays are reflected 
as an intense parallel beam.