Question

A ray of light is incident on the surface of seperation of a medium at an angle `45^(@)` and is refracted in the medium at an angle `30^(@)`. What will be the velocity of light in the medium?
A. `1.96 xx 10^(8) m//s`
B. `2.12 xx 10^(8) m//s`
C. `3.18 xx 10^(8) m//s`
D. `3.33 xx 10^(8) m//s`

Answer 1

Correct Answer - B
`i = 45^(@), r = 30^(@), v_(a) = 3 xx 10^(8)m//s, v_(m) = ?`
`mu_(m) = (sin i)/(sin r) = (v_(a))/(v_(m))`
`:. v_(m) = (v_(a) sin r)/(sin i) = (3 xx 10^(8) xx sin 30)/(sin 45)`
`= (3 xx 10^(8) xx 0.5)/(0.707) = 2.12 xx 10^(8) m//s`.