Question

A convex lens of focal length f is cut into two equal parts perpendicular to its principal axis. What happens to the focal length

Answer 1

Convex Lens..

f= f

Hence . the focal length is the distance between the optical centre and f.

so.. when the lens is cut perpendicular to principal axis then it means lens is divided into two parts from its diameter.

so. If lens is cut along the principal axis then there will be no change in the focal length of lens. but it is cut perpendicular to principal axis, then focal length will be twice the original one.

So focal length became twice the original (of cut halves)

$\huge\mathfrak\red{Thanks.}$