Assertion : The mirrors used in search lights are parabolic and n… - Vidyadip

MCQ

Assertion : The mirrors used in search lights are parabolic and not concave spherical.
Reason : In concave spherical mirror the image formed is always virtual.

A
Both assertion and reason are true and the reason is the correct explanation of the assertion.
B
Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
✓
The assertion is true, but the reason is false.
D
The assertion is false, but the reason is true.

✓

Answer

Correct option: C.

The assertion is true, but the reason is false.

The assertion is true, but the reason is false
Correct explanation:
In search lights, we need an intense parallel beam of light. If a source is placed at the focus of a concave spherical mirror only paraxial rays are rendered parallel. Due to large aperture of mirror, marginal rays give a divergent beam. But in case of parabolic mirror, when source is at the focus, beam of light produced over the entire cross – section of the mirror is a parallel beam.

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