Question

What is the focal length of a double convex lens for which the radius of curvature of each surface is 50 cm and the refractive index of glass is 1.50 ?

Answer 1

hey dear your answer is here..
f=R/2
f=50/2=25 cm

Answer 2

Answer: The focal length of a double convex length is 50 cm.

Explanation:

Given that,

Radius of curvature of each surface = 50 cm

First radius of curvature $R_{1} = R$

Second radius of curvature $R_{2} = -R$

Refractive index = 1.50

We know that,

$\dfrac{1}{f} = (\mu -1)[\dfrac{1}{R_{1}}-\dfrac{1}{R_{2}}]$....(I)

Now, put the value of $R_{1}$ and $R_{2}$ in equation (I)

$\dfrac{1}{f} = (1.50 -1)[\dfrac{1}{50}+\dfrac{1}{50}]$

$\dfrac{1}{f} = \dfrac{1}{50 cm}$

$f = 50 cm$

Hence, the focal length of a double convex length is 50 cm.