Assertion : The focal length of an equiconvex lens placed in air to radius of curvature of either face.
Reason : For an equiconvex lens radius of curvature of both the faces is same.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true and reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

B

Explanation

For an equiconvex lens, `R_(1) = R_(2) = R`
From, `1/f = (mu-1) (1/(R_(1)) - 1/(R_(2)))`
[using lens maker's formula]
For lens, `mu = 1.5` placed in air.
Therefore, `1/f = (1.5-1) 2/R rArr f = R`.