Question

focal length of plano convex lens when its radius of curvature of the surface is R and n is the refractive index of the lens

Answer 1

I/f=(n-1)(1/r¹-1/r2)

Answer 2

we know that

1/ f = (n-1)R

where

n=refractive index

R=radius of curvature

now

atq

1/f=(n-1)R

f=1/(n-1)R

hope it helps

you