Solveeit Logo
Login

Question

Question: A thin double convex lens has radii of curvature each of magnitude 40 *cm* and is made of glass with...

A thin double convex lens has radii of curvature each of magnitude 40 cm and is made of glass with refractive index 1.65. Its focal length is nearly

A

20 cm

B

31 cm

C

35 cm

D

50 cm

Answer

31 cm

Explanation

Solution

By using f=R2(μ−1)f = \frac { R } { 2 ( \mu - 1 ) } ⇒ f=402(1.65−1)=30.7 cm≈31 cmf = \frac { 40 } { 2 ( 1.65 - 1 ) } = 30.7 \mathrm {~cm} \approx 31 \mathrm {~cm}