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WHAT IS MEANING OF REFRACTIVE INDEX? 

Refractive Index

The refractive index is a constant for a given pair of materials. It can be defined as

speed of light in material 1

speed of light in material 2

This is usually written 1n2 and is the refractive index of material 2 relative to material 1. The incident light is in material 1 and the refracted light is in material 2.

If the incident light is in a vacuum this value is called the absolute refractive index of material 2. This is the value given in data books.

By definition the refractive index of a vacuum is 1. In practice, air makes little difference to the refraction of light with an absolute refractive index of 1.0008, so the value of the absolute refractive index can be used assuming the incident light is in air.

Material

Absolute Refractive Index
Air 1.0008
Water 1.330
Glass, soda-lime 1.510
Diamond 2.417
Ruby 1.760

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Refractive index of of medium 1 with respect to the refractive index of medium 2 is equal to the speed of light in medium 2 with respect to the speed of light in medium 1

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 The ratio of the speed of light in a vacuum to the speed of light in a medium under consideration. Also called refractive index.


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The index of refraction is defined by

(1)

where c is the speed of light and  is the phase velocity. It gives the amount of refraction which takes place for light passing from one medium to another. A complex index of refraction can be defined for substances which absorb as well as refract as

(2)

where k is the wavenumber,  is the angular frequency,  is the electric permittivity, and  is the electrical conductivity.

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he refractive index or index of refraction of a substance is a measure of the speed of light in that substance. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium.The velocity at which light travels in vacuum is a physical constant, and the fastest speed at which energy or information can be transferred. However, light travels slower through any given material, or medium, that is not vacuum. 

A simple, mathematical description of refractive index is as follows:

n = velocity of light in a vacuum / velocity of light in medium

Hence, the refractive index of water is 1.33, meaning that light travels 1.33 times as fast in a vacuum as it does in water.

As light exits a medium, such as air, water or glass, it may also change its propagation direction in proportion to the refractive index (see

Snell's law

). By measuring the angle of incidence and angle of refraction of the light beam, the refractive index

n

can be determined. Refractive index of materials varies with the frequency of

radiated light

. This results in a slightly different refractive index for each

color

. The cited values of refractive indexes, such as 1.33 for water, are taken for

yellow

light of a

sodium

source which has the wavelength of 589.3 nanometers.

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Measure of the bending or refraction of a beam of light on entering a denser medium (the ratio between the sine of the angle of incidence of the ray of light and the sine of the angle of refraction). It is constant for pure substances under standard conditions. Used as a measure of sugar or total solids in solution, purity of oils, etc.

 

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 The refractive index or index of refraction of a substance is a measure of the speed of light in that substance. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium.The velocity at which light travels in vacuum is a physical constant, and the fastest speed at which energy or information can be transferred. However, light travels slower through any given material, or medium, that is not vacuum. 

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Hi Devika!

The refractive index of a medium is a measure of the speed of light in that medium. It is expressed as a ratio of the speed of light in vacuum relative to that in the medium under consideration. Light travels slower through any given material, or medium, as compared to that in vacuum.

Good work @ Chandni, @Gunjan and @ Kritartha!! Keep posting!!

Cheers!!

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