If the critical angle for total internal reflection from a medium to vacuum is 30°. Then the speed of light in the medium is?

3x108 m/s 2x108 m/s 1.75x108 m/s 1.5x108 m/s

1.5x108 m/s

Refractive index μ = 1/sinθc                            = 1/sin30 =2 Refractive index μ = c/v                         v = 3x108 / 2 = 1.5x108 m/s