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°

option B is correct

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

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°