Question

Arrange the following data according to the increasing order of Radius of curvature of the given plano convex lenses
a) plano convex lens of f $=$40 cm and $\mu =$1.5
b) plano convex lens of f $=$20 cm and $\mu =$1.6
c) plano convex lens of f $=$20 cm and $\mu =$1.5
d) plano convex lens of f $=$25 cm and $\mu =$1.5

• A. b, a, d, c
• B. a, b, c, d
• C. c, b, d, a
• D. c, b, a, d

Answer 1

The correct option is C c, b, d, a

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

$f=\frac{R_1}{\mu -1}\Rightarrow R=\left(f\right)(\mu -1)$

$R_c=\left(20\right)\left(\frac{1}{2}\right)=10cm$

$R_A=40\times \frac{1}{2}=20cm$

$R_b=20\times \frac{6}{10}=12cm$

$R_d=25\times \frac{5}{10}=12.5$