Question

4 The adsolute refraction indices of glass and water are
4/3 and 3/2 respectively. If the
speed of light in glass i 2×10/8 m/s, calculate the
speed of light in (i) Vacuum, (ii) water
​

Answer 1

Answer:

Refractive index of glass, ng =

4 Speed of light in vacuum

3

2 x 108

Speed of light in vacuum Speed of light in glass

Speed of light in vacuum = 2.6 x 108

But note that ideally the speed of light in vacuum is 3 x 108 m/s.

Refractive index ofwater, nw = Speed of light in vacuum Speed of light in water

3

2.6 x 108

Speed of light in water

Speed of light in water 1.73 x 10 m/s.