Question

Calculate the radius of curvature of an equi concave lens of refractive index 1.5 , when it is kept in a medium of refract
ive index 1.4 to have a power of -50

Answer 1

Answer:

Focus of a lens is given by:

1/f= (n-1) (1/R1- 1/R2)  

where f is the focal length of the lens and R1 and R2 are the radius of the refracting surface on the side of the object and on the other side respectively.

Explanation:

Let the radius be R.

R1= -R  and   R2= R

Power of the lens, P=50 D= 50 m-1

Refractive index, n=1.5/1.4 (first medium/ second medium)

We know that,

P=  1/f= (n-1) (1/R1- 1/R2)  

By putting the values of P and n,we will get the value of R.