# Density and refractive index relationship tips

### Refractive index - Wikipedia

Equation Relating Density, Refractive Index, and Molecular Weight for Paraffins and Conversion of Refractive Dispersions to Other Wave-Length Intervals. Density. A scatter plot showing a strong correlation between glass density and refractive index for different glasses. Relation. From absorption data calculate the band gap. Using this band gap value and substituting in below equation, you can get refractive index. n = {[3 * root of (20/ Eg)].

A few examples are given in the adjacent table. These values are measured at the yellow doublet D-line of sodiumwith a wavelength of nanometersas is conventionally done.

Almost all solids and liquids have refractive indices above 1. Aerogel is a very low density solid that can be produced with refractive index in the range from 1. Most plastics have refractive indices in the range from 1.

Moreover, topological insulator material are transparent when they have nanoscale thickness. These excellent properties make them a type of significant materials for infrared optics. The refractive index measures the phase velocity of light, which does not carry information.

This can occur close to resonance frequenciesfor absorbing media, in plasmasand for X-rays.

### optics - Relation between intensity of light and refractive index - Physics Stack Exchange

In the X-ray regime the refractive indices are lower than but very close to 1 exceptions close to some resonance frequencies. Since the refractive index of the ionosphere a plasmais less than unity, electromagnetic waves propagating through the plasma are bent "away from the normal" see Geometric optics allowing the radio wave to be refracted back toward earth, thus enabling long-distance radio communications.

See also Radio Propagation and Skywave. Negative index metamaterials A split-ring resonator array arranged to produce a negative index of refraction for microwaves Recent research has also demonstrated the existence of materials with a negative refractive index, which can occur if permittivity and permeability have simultaneous negative values.

The resulting negative refraction i. Ewald—Oseen extinction theorem At the atomic scale, an electromagnetic wave's phase velocity is slowed in a material because the electric field creates a disturbance in the charges of each atom primarily the electrons proportional to the electric susceptibility of the medium.

### Optical Density and Light Speed

Similarly, the magnetic field creates a disturbance proportional to the magnetic susceptibility. As the electromagnetic fields oscillate in the wave, the charges in the material will be "shaken" back and forth at the same frequency. The light wave traveling in the medium is the macroscopic superposition sum of all such contributions in the material: This wave is typically a wave with the same frequency but shorter wavelength than the original, leading to a slowing of the wave's phase velocity.

Most of the radiation from oscillating material charges will modify the incoming wave, changing its velocity. In Unit 12 of The Physics Classroom Tutorialthe mechanism of energy transport by an electromagnetic wave was briefly discussed. Here we will look at this method in more detail.

An electromagnetic wave i. This value is the speed of light in a vacuum. When the wave impinges upon a particle of matter, the energy is absorbed and sets electrons within the atoms into vibrational motion.

## Optical Density and Light Speed

If the frequency of the electromagnetic wave does not match the resonant frequency of vibration of the electronthen the energy is reemitted in the form of an electromagnetic wave. This new electromagnetic wave has the same frequency as the original wave and it too will travel at a speed of c through the empty space between atoms. The newly emitted light wave continues to move through the interatomic space until it impinges upon a neighboring particle.

The energy is absorbed by this new particle and sets the electrons of its atoms into vibration motion.

• Relationship between density and refractive index of inorganic solids
• Applied Optics
• Refractive index

And once more, if there is no match between the frequency of the electromagnetic wave and the resonant frequency of the electron, the energy is reemitted in the form of a new electromagnetic wave. The cycle of absorption and reemission continues as the energy is transported from particle to particle through the bulk of a medium.

Every photon bundle of electromagnetic energy travels between the interatomic void at a speed of c; yet time delay involved in the process of being absorbed and reemitted by the atoms of the material lowers the net speed of transport from one end of the medium to the other.

Optical Density and the Index of Refraction Like any wave, the speed of a light wave is dependent upon the properties of the medium. In the case of an electromagnetic wave, the speed of the wave depends upon the optical density of that material. The optical density of a medium is not the same as its physical density.

What is Refractive Index ? CLASS X : CBSE / ICSE : Refraction Of Light 02

The optical density of a material relates to the sluggish tendency of the atoms of a material to maintain the absorbed energy of an electromagnetic wave in the form of vibrating electrons before reemitting it as a new electromagnetic disturbance.