Physics for IGCSE & O level - Rays And Waves (Section 6 - No. 25)

What is the formula for calculating the refractive index?

refractive index = speed of light in medium / speed of light in vacuum

refractive index = speed of light in vacuum / speed of light in medium

refractive index = sin i / sin r

refractive index = sin r / sin i

The refractive index is calculated by dividing the speed of light in a vacuum by the speed of light in the medium.