Dispersion

Dispersion Physics is the breaking or scattering of something. 

From our childhood days, we love to see a rainbow. A rainbow is the dispersion or scattering of seven colours of light and giving a beautiful scenic view of the sky.

So, we know that dispersion Physics plays an important role in our day-to-day life. 

Dispersion is a phenomenon that we see in the glass of water and the dispersion of water in the glass is similar to the dispersion of tiny water droplets in the rainbow formation; this article discusses the same in detail.

Define Dispersion of Light

Light refers to what we see or to a piece of the electromagnetic spectrum that operates on the optical telescope, especially on the ground, and sometimes, it means the entire electromagnetic spectrum or any electromagnetic radiation.

When this light gets split into different colour lights having varying wavelengths, it is the dispersion of light. The light that we can see is the visible spectrum, the below image shows the wavelengths of each light in the spectrum in nanometers or nm:

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Dispersion Definition Physics

In Physics, dispersion is the division of white light into seven colours of varying wavelengths and frequencies in the sequence of VIBGYOR.

Wave dispersion is observed in wave motion of light, water. It is a phenomenon associated with the propagation of individual waves at respective speeds that totally depend on their wavelengths. 

For instance, ocean waves move at speeds directly proportional to the square root of their wavelengths; these speeds vary from a few feet per second for disturbances/ripples to hundreds of miles per hour for tsunamis.

What Is Dispersion??

From the above text, we understood that dispersion is the scattering of something into small or tiny particles. 

The dispersion optics talks about the prism, which is kept still, and the light when passed through breaks or disperses into seven colours, i.e., VIBGYOR.

Here, V is for violet, I is for Indigo, B is for blue, G is for green, Y is for yellow, O is for orange, and R is for red.

Here, we talked more about white light, so do you know what white light is and what is dispersion in Physics?

What is Dispersion in Physics?

The complete blend of all the wavelengths of the visible spectrum is known as white light. This indicates that if a person has a beam of light of the visible spectrum, i.e., all the colours of the rainbow, and focuses all of them onto a single spot, the combination of all colours results in a beam of white light.

White light or visible light has a range above infrared rays. At its peak, the Sun emits visible light. However, combining the entire emission power spectrum passes all wavelengths showing that the Sun emits slightly more amount of infrared rays than visible light.

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Dispersion Optics in Physics

Dispersion Optics is the phenomenon in which the phase velocity of a wave depends on its frequency. Media having dispersion optics characteristics is termed dispersive media. We often use the term chromatic dispersion for generalization.

However, the term dispersion optics in Physics is used in the field of optics to describe light and other electromagnetic waves, it applies to any sort of wave motion like acoustic dispersion of sound, seismic waves, in gravity waves, oceanic waves, and also for telecommunication signals along transmission lines, like a coaxial cable or optical fibre.

Dispersion Optics

To understand what is dispersion optics, let’s perform a simple experiment:

Apparatus required for the dispersion optics experiment:

• Place a glass prism inside the darkroom.

• Place the prism in a position where the direct sunlight can fall upon its surface.

• Make a small hole in the window shutter of the room so that the sunlight can pass through this hole like a narrow beam.

• Fix a white sheet on another side of the wall where the sun says can directly fall on the prism and get the best result via the reflection. 

What do you observe after this process? If you look carefully, the light splits into a spectrum of colours. The sunlight (white light) is having colour combinations as violet, indigo, blue, green, yellow, orange, and red.

Scientists have named these combinations of colours VIBGYOR. The letters in the word define each colour that is present in the sunlight.

The result can be observed in the below diagram:

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Result of the Experiment:

When a beam of light is passed through a refracting medium like a glass prism, the light that is least refracted is the red light and highly refracted in Violet.

The sequence of VIBGYOR can be seen in the image below:

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Application of Dispersion

We find the application of dispersion in many other circumstances, such as group velocity dispersion or GVD that causes pulses to scatter in optical fibres, degrading/decreasing the intensity of signals over long distances; also, as a cancellation between group-velocity dispersion and nonlinear effects leads to soliton waves.