Question

What do you understand by the statement that refractive index of ordinary glass is 1.5?

Answer 1

A refractive index of 1.5 for ordinary glass means that light travels 1.5 times faster in vacuum than in glass.

Thus, V = `c/1.5`; using c = 3 × 10⁸ m/s, the speed of light in ordinary glass is approximately 2.0 × 10⁸ m/s.