Question

A plate glass window (n? 1.5) has a thickness of 4.0 ? 10?3 m. Light is incident on the plate at an angle of 30°

.a. Compute the angle of refraction.

b. Compute the velocity of light passing through the plate

c. How long does it take light to pass through the plate?

Answer 1

a) Angle of refraction

Snell's law n₁ sin₁ = n₂sin₂

  1 × sin 30° = 1.5 ×sin₂ (n_{1= refractive index ,air)} sin₂   = 1 × 0.5 / 1.5

₂   = sin^-1( 0.3333)

Angle of refraction,_2. = 19.42°

b) Velocity of light passing through glass plate

V = C / n

C = Speed of light in vaccum

n = refractive index of glass plate

V =2.99 x10^8 / 1.5

V    2.0x10^8 m / s

c) Time = thickness / Velocity

There is no clear provision regard the thickness,

If the thickness is 4.0 m , then

Time = 4.0 / 2.0x10^8

Time =2.0x10^-8 seconds