The refractive index, also called the index of refraction, is defined as the quotient of the speed of light as it passes through two media. It is a dimensionless number that depends on temperature and on the wavelength of the light beam. In simple words, the refractive index describes how fast a light beam travels through media, and this relationship is described by the formula:
n = c / v
n is the index of refraction
c is the speed of light in a vacuum (or air)
v is the speed of light in the media (e.g. water, olive oil, etc.)
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