If the speed of light in a substance is 2.26 x 10^8 m/s, what is the index of refraction of that substance?

1.33

Explanation:

speed of light in vacuum, c = 3 x 10^8 m/s

speed of light in medium, v = 2.26 x 10^8 m/s

The refractive index of the medium is given by

μ = speed of light in vacuum / speed of light in medium

μ = (3 x 10^8) / (2.26 x 10^8)

μ = 1.33