what is refrective index of a material explain with physical meaning?

Answer 1

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
DEFINITON:A property of a material that changes the speed of light, computed as the ratio of the speed of light in a vacuum to the speed of light through the material. When light travels at an angle between two different materials, their refractive indices determine the angle of transmission (refraction) of the light beam. In general, the refractive index varies based on the frequency of the light as well, thus different colors of light travel at different speeds. High intensities also can change the refractive index.

The refractive index of a vacuum is 1.0, and air is a tiny fraction greater than 1.0. The higher the index, the slower the speed of light through the medium, because the speed through the material is the speed of light (c) over the refractive index (n), thus speed = c/n.

Answer 2

The index of refraction is often used in problems that deal with the interaction of light and matter. Light is electromagnetic radiation, and matter consists of atoms which in turn consist of a nucleus and a number of electrons. Electrons are charged particles, and charged particles interact with electromagnetic radiation (actually the nucleus is also a charged particle, but we will ignore its influence here to simplify the treatment). Loosely speaking, the interaction of the electrons and the electromagnetic radiation causes the radiation (often described as a traveling wave) to slow down while traveling through a medium. The index of refraction is a measure of how much the radiation is slowed down and is defined as follows:

The speed of light (electromagnetic radiation) in vacuum (i.e. empty space) is given by c (~3*10^8 m/s).

While traveling through a material, light will move at a speed v = c/n.

n is the index of refraction of the material in question (thus the index of refraction of vacuum is 1, this is also often taken as the index of refraction for air).

Now, in the discussion above it was assumed that the light was monochromatic (i.e. it had a single frequency component), this would be the case if the electromagnetic radiation field had the simple form of a continuous wave (like cos(wt) or sin(wt) where w is the angular frequency). However, in many materials, the index of refraction is a function of the frequency of light (a function of w), so if the electromagnetic radiation is a pulse (it has many frequency components) as opposed to a continuous wave (it has a single frequency component), then the different frequency components would travel at different rates in the material. This phenomenon is known as dispersion and it can be a serious problem for long distance optical communications.

Answer 3

Refractive index, let's call it n, of a material is the speed of light in a vacuum divided by the speed of light in that material. It depends on the electrical and magnetic properties of the material. The refractive indices of transparent substances are usually between 1 and 2. The values of n for most glasses are around 1.4. The highest n I know anything about is for diamond, and it's close to 2. For water, n is about 1.3. The way it was explained to me when I was about 12 was, imagine a column of soldiers marching across flat dry ground. Each row of soldiers is a wavefront. They long column is a light ray. They reach a swamp with a straight boundary, and they cross the boundary at an angle. They have to maintain formation. For each row to stay straight, the column has to bend towards the line which is perpendicular to the boundary, because the swamp slows them down. The perpendicular line is called the normal. In optics, Snell's Law says that n= (sin i)/(sin r) where i= the angle the light ray makes with the normal outside the slow medium, called the angle of incidence, and r = the angle it makes with the normal inside the medium, called the angle of refraction. It's an easy experiment you can try yourself with a glass block, a protractor to measure angles, a calculator to work out sines, and a device to give you a narrow light ray, like a laser pointer. Try varying the angle at which the ray enters the block, and you'll find that sin i/ sin r stays the same for a particular material. Use a different type of glass and sin i / sin r will have a different, constant value.

Answer 4

R.I of a material wrt air actually gives us the idea, that by how much the refracted ray is going to bend or deviate from its original path.

Remember RI = 1/ SIN c, where c is the critical angle

= ratios of the velocities

= ratio of sin i to sin r

Answer 5

refractive index is the ratio of speed of liaght in vaccum to that of same in medium.its difficult to explain but with practise problems and numericals,you will understand it.
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Answer 6

i think ,its an angle made by the ray of light to the normal when it enters into hte material.

Answer 7

I think the below link is good to study and understand.

Answer 8

it is=speed of light in vaccuum/speed of light in that substance.