Question

The refractive index of diamond relative to air is 2.42 and that of glass is 1.51. How much faster does light travel in glass than in diamond?

Answer 1

Given:

Refractive index of diamond relative to air, n_d = 2.42

Refractive index of glass relative to air, n_g = 1.51

To Find: How much faster does light travel in glass than in diamond?

Formula:

The refractive index of a medium (n) relates the speed of light in a vacuum (or air) (c) and the speed of light in that medium (v) as:

n = `c/v`

From this,

v = `c/n`

To find how many times faster light travels in glass than in diamond,

`v_g/v_d = (c/n_g)/(c/n_d) = n_d/n_g`

Calculation:

`v_g/v_d = 2.42/1.51`

`v_g/v_d` = 1.60

∴ Light travels 1.60 times faster in glass than in diamond.