Question

A convex lens is put 10 cm away from the light source to get a sharp age on screen 10 cm away from lens , then a glass slab of refractive index 1.5

Answer 1

refractive index of light in air is 3×10 rise to 8
refractive index of glass medium is 1.5 then the refractive index is =c/v
3×10^8/1.5
=2×10^8

Answer 2

Answer:

The focal length of the lens is 5 cm.

Explanation:

Given that,

Object distance = -10 cm

Image distance = 10 cm

Refractive index = 1.5

Suppose we find the focal length of convex lens

Using formula of convex lens

$\dfrac{1}{v}-\dfrac{1}{u}=\dfrac{1}{f}$

Where, v = image distance

u = object distance

Put the value into the formula

$\dfrac{1}{10}+\dfrac{1}{10}=\dfrac{1}{f}$

$f=5\ cm$

Hence, The focal length of the lens is 5 cm.