The index of refraction of a certain liquid is 2.1. What is the critical angle for a light ray traveling in this liquid toward a flat layer of air above it?

28.42°

Explanation:

Critical Angle:This is the incident angle at which the angle of refraction is 90° when light passes from denser to less dense medium

from Refraction,

1/n = sinc ... Equation 1

Where n = refractive index of the liquid, c = critical angle.

make c the subject of the equation

c = sin⁻¹ (1/n) ... Equation 2

Given: n = 2.1

Substitute the value of n into equation 2

c = sin⁻¹ (1/2.1)

c = sin⁻¹ (0.476)

c = 28.42°

Hence the critical angle = 28.42°