The equiconvex lens has focal length f. If it is cut perpendicular to the principal axis passing through optical centre, then focal length of each half is

Options

(a) f/2
(b) f
(c) 3f/2
(d) 2f

Correct Answer:

2f

Explanation:

When an equiconvex lens is cut parallel to principal axis, then focal length remains the same and when the lens is cut perpendicular to principal axis, then its focal length becomes twice the original.