Q. A thin convex lens of crown glass having refractive index 1.5 has power 1 D. What will be the power of similar convex lens refractive index 1.6?
A) 0.6 D
B) 0.8 D
C) 1.2 D
D) 1.6 D
Explanation
(c) $P = \frac{1}{f} = (\mu - 1)\left\lbrack \frac{1}{R_{1}} - \frac{1}{R_{2}} \right\rbrack$
$Hence,\ \ \ \frac{P_{2}}{P_{1}} = \left( \frac{\mu_{2} - 1}{\mu_{1} - 1} \right)$
$ie,\ \ \frac{P_{2}}{1} = \frac{1.6 - 1}{1.5 - 1}$
$Hence,\ P_{2} = 1.2$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.