Question

The speed of light in air is 3.0 x 10^8 m/s. The speed of light in particular glass is 2.3 x 10^8 m/s. Use the information to determine the angle of refraction of light which travels from the glass into air, if the angle of incidence on the glass/air boundary is 25° . Draw a diagram.

Answer 1

Answer:

33.61°

Explanation:

Refractive index is equal to velocity of the light 'c' in empty space divided by the velocity 'v' in the substance.

Or ,

n = c/v.

v is the velocity in the medium  (2.3 × 10⁸ m/s)

c is the speed of light in air = 3.0 × 10⁸ m/s

So,  

n = 3.0 × 10⁸ /  2.3 × 10⁸

n = 1.31

Using Snell's law as:

$n_i\times {sin\theta_i}={n_r}\times{sin\theta_r}$

Where,  

${\theta_i}$  is the angle of incidence  ( 25.0° )

${\theta_r}$ is the angle of refraction  ( ? )

${n_r}$ is the refractive index of the refraction medium  (air, n=1)

${n_i}$ is the refractive index of the incidence medium (glass, n=1.31)

Hence,  

$1.31\times {sin25.0^0}={1}\times{sin\theta_r}$

Angle of refraction = $sin^{-1}0.5536$ = 33.61°