Question

A plano convex lens is made of refractive index $1.6$. The radius of curvature of the curved surface is $60cm$. The focal length of the lens is _______

Answer 1

$R_1=60cm,R_2=\alpha ,\mu =1.6$

$\frac{1}{f}=(\mu -1)(\frac{1}{R_1}-\frac{1}{R_2})$

$\frac{1}{f}=(1.6-1)\left(\frac{1}{60}\right)$

$f=100cm$