Question

Newton’s rings are formed with reflected light of wavelength 589 nm using a plano-
convex lens and a plane glass plate with a liquid between them. The diameter of the
15th ring is 5.1 mm and radius of curvature of the curved surface of the lens is 1 m.
Calculate the refractive index of the liquid if the ring is dark.

Answer 1

Answer on Question #74819-Physics-Optics

Newton's rings are formed with reflected light of wavelength 589 nm using a plano-convex lens and a plane glass plate with a liquid between them. The diameter of the 15th ring is 5.1 mm and radius of curvature of the curved surface of the lens is 1 m. Calculate the refractive index of the liquid if the ring is dark.

Solution

For the dark ring system:

$$\frac {\mu d _ {n} ^ {2}}{4 R} = n \lambda$$ $$\mu = \frac {4 R}{d _ {n} ^ {2}} n \lambda$$

The refractive index of the liquid is

$$\mu = \frac {4 (1)}{(0 . 0 0 5 1) ^ {2}} (1 5) 5 8 9 \cdot 1 0 ^ {- 9} = 1. 3 6.$$

Answer: 1.36.

Answer provided by https://www.AssignmentExpert.com