Question

A transparent sphere of radius 6cm is kept in air. An object is placed at 12 cm distance from the surface of the sphere and its real image is formed at the same distance from the second surface of the sphere. Find the refractive index of the material of the sphere ?​

Answer 1

Explanation:

Given: A transparent sphere of radius R and refractive index μ is kept in the air.

To find the distance from the surface of the sphere where a point should be placed so as to form a real image at the same distance from the other side of the sphere

Solution:

Using the equation,

μ2/v - μ1/u = μ2−μ1/R

For the refraction at the first surface of the sphere,

(air to glass)

μ/∞ - 1/-x = μ−1/R, Here x is the distance of point object from the sphere, as shown in above fig.

⟹1/x = μ−1/R

=> x= R/μ−1

Hence the object should be placed this distance from the surface of the sphere in order to get real image.