Question

Assertion (A): Mirror formula can be applied to a plane mirror.
Reason (R): A plane mirror is a spherical mirror of infinite focal length
(a) Both assertion and reason are true and reason is the correct explanation of the assertion
(b) Both assertion and reason are true and reason is not the correct explanation of the assertion
(c) Assertion is true but reason is false
(d) Both assertion and reason are false

Answer 1

Answer:

(c) Assertion is true but reason is false

Answer 2

The correct option is (c) Assertion is true but reason is false

Assertion (A): Mirror formula can be applied to a plane mirror.

Mirror formula is stated below:

$\frac{1}{f} =\frac{1}{u} +\frac{1}{v}$

We know that focal length of plane mirror = ∞

∴ $\frac{1}{infinity} =\frac{1}{u} +\frac{1}{v}$

∴ $0 =\frac{1}{u} +\frac{1}{v}$

∴ $\frac{1}{u} =-\frac{1}{v}$

∴ u = -v

The above derivation proves that the image distance is equal to the object distance and the image is formed behind the mirror.

This statement is true for the plane mirror. Thus, the mirror formula can be applied to the plane mirror.

Reason (R): A plane mirror is a spherical mirror of infinite focal length

A plane mirror has an infinite focal length, but it is not a spherical mirror.

Thus, the reason statement is false.