Q. A plano convex lens is made of glass of refractive index 1.5. The radius of curvature of its convex surface is $R$. Its focal length is
A) $\frac{R}{2}$
B) $R$
C) $2R$
D) $1.5\ R$
Explanation
(c) $f = \frac{R}{(\mu - 1)} = \frac{R}{(1.5 - 1)} = 2R$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.