Question

Light travels from air (n = 1) into a tank of water (n = 1.33) and continues on into a layer of glass (n = 1.5). The light strikes the air-water interface at θi = 45°. What angle does the beam make to the normal line inside the glass (i.e., θr in the glass)? A) 20° B) 28° C) 36° D) 44°

Answer 1

option B is correct

beam make to the normal line inside the glass angle is 28°

Step-by-step explanation:

Given data

air (n = 1)

water (n = 1.33)

glass (n = 1.5)

air-water interface at θi = 45°

to find out

angle does the beam make to the normal line inside the glass i.e θr

solution

we know here in air water interface

n1 = 1 and angle 45° and n2 = 1.33

n1×Sin(θ)i = n2×Sin(θ)r ...............1

so now put all value in equation 1

1×Sin45 = 1.33× sin(θ)r

(θ)r = 32.12°

so this is here (θ)r refraction angle in the water

and

we know this angle act as incident angle for water glass

so that

n2×Sin(θ)r = n3×Sin(θ)g ....................2

here n3 = 1.5 and n2 = 1.33 and (θ)r = 32.12°

so

1.33 × Sin 32.12 = 1.5×Sin(θ)g

(θ)g = 28 degree

so option B is correct

beam make to the normal line inside the glass angle is 28°