A double convex lens of focal length 25 cm is divided into two equal halves in thickness. Find the focal length of each half.

Explanation

Focal length of double convex lens `=f=+25cm`
Let `f_(1)=f_(2)=f.=` Focal length of each half piece of convex lens
We know `1/f=1/(f_(1))+1/(f_(2))`
`1/25=1/(f.)+1/(f.)`
`1/25=(1+1)/(f.)=2/(f.)`
`impliesf.=2xx25=50cm`