The index of refraction is the ratio of the speed of light in that medium to the speed of light in vacuum. If it takes a pulse of 500 nm light 0.15 ns to travel through a 3 cm block of glass, what is the index of refraction of the glass?

Question

Quizplus · Accepted Answer

The speed of light in the glass is distance/time = 3 cm / 0.15 ns = 20 cm/ns. The speed of light in vacuum is approximately 30 cm/ns. The index of refraction is the ratio of these speeds: 30 cm/ns / 20 cm/ns = 1.5.

The Index of Refraction Is the Ratio of the Speed