Question

The power of a lens having a refractive index of 1.25 is 3 diopters. When placed in a liquid, its power is 2 diopters. The refractive index of the liquid is:

a. 1.5
b. 1.25
c. 1.75
d. 2

Answer 1

The refractive index of the liquid is (a) 1.5.

Step-by-step explanation:

The refractive index of a liquid can be determined by using the lens formula:

1/f = (n_l - n)/R

Where,

• f is the focal length of the lens
• n_l is the refractive index of the lens in air
• n is the refractive index of the liquid
• R is the radius of curvature of the lens

Given that the power of the lens is 3 diopters when the refractive index of the lens is 1.25, and the power becomes 2 diopters when placed in a liquid, we can use the lens formula to find the refractive index of the liquid:

1/3 = (1.25 - n)/R

1/2 = (1.25 - n)/R

Solving these equations, we find that the refractive index of the liquid is 1.5.