The speed of light in vacuum is exactly 299,792,458 m/s. A beam of light has a wavelength of 621 nm in vacuum. This light propagates in a liquid whose index of refraction at this wavelength is 1.18.What is the speed of this light in the liquid

2.54*10^8 m/s

Explanation:

Given that

Speed of light in space, c = 299792458 m/s

Wavelength of the beam of light, λ = 621 nm or 621*10^-9 m

Index of refraction of the liquid, n = 1.18

Speed of light in the liquid, v = ?

The index of refraction of an optical material, n is given by the following formula.

n = c/v, and if we substitute directly, we have

1.18 = 299792458 / v, if we make v subject of formula, we have

v = 299792458 / 1.18

v = 2.54*10^8 m/s

3. dark matter

empty space could also be a simple vacuum