Question

A concave mirror is used as reflector in torches, head lights of automobiles etc.obtain a parallel beam of lights . states the position of the sources of lights on the principal axis to obtain the parallel beam.
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Answer 1

Explanation:

The source should be placed at the focus of the concave mirror to obtain parallel beam of light.

Hope it helps..

Answer 2

Answer:

because concave mirror expand the light in all directions