The absolute refractive index of a light beam at a temperature from vacuum to atmosphere n = 1.3.

The absolute refractive index of a light beam at a temperature from vacuum to atmosphere n = 1.3. Determine the speed of the beam passing through the air.

1) The absolute refractive index of light of some medium is equal to the ratio of the speed of light in vacuum c to the speed of light v in this medium: n = c / v.
2) To find the speed of light in air, we express from here v. We get: v = c / n. Since the speed of light in vacuum is c = 300000 km / s, then: v = (300000 km / s) / 1.3 ≈ 231000 km / s.
ANSWER: v ≈ 231000 km / s.