Question

Problem 18.49 Part A What is the angle of incidence in air of a light ray whose angle of refraction in glass is half the angle of incidence? Express your answer using two significant figures.

Answer 1

we know, for glass refractive index = 1.5

let theta_i is the angle of incidence

and theta_r is the angle of refraction

given, theta_r = theta_i/2

Apply Snell's law

n1*sin(theta_i) = n2*sin(theta_r)

1*sin(theta_i) = 1.5*sin(theta_r)

2*sin(theta_i/2)*cos(theta_i/2) = 1.5*sin(theta_i/2)

cos(theta_i/2) = 1.5/2

theta_i/2 = cos^-1(0.75)

theta_i/2 = 41.4

theta_i = 41*4*2

= 82.8 degrees <<<<<<<<<---------------Answer