The phenomenon of separation of colors in white light is called dispersion. The collection of these colors is called a spectrum. A good example of a color spectrum is the rainbow. Rainbows occur when sunlight is refracted by water droplets during the rainy season. We can see a rainbow when it rains or after it stops raining or when we see a fountain with the sun behind us. The Sunlight falling on water droplets floating in the air is refracted and separated into its seven colors. Therefore, the water droplets floating in the air act as a glass prism. A rainbow is formed when the light ray entering the droplet undergoes a complete reflection before exiting it.
Color Spectrum - Rainbow
The visible light spectrum is obtained from materials in a flammable state. And the agitated atoms in the gases emit visible light spectrums.
Its wavelength ranges from $\mathrm{4\times 10^{-7}m\:to\:7\times 10^{-7}m}$
And its frequency range is from $\mathrm{7\times 10^{14}Hz\:to\:4\times 10^{14}Hz}$
Subject to reflection, refraction, interference, diffraction, and polarisation. Also used in photography. The visible light is used to study the molecular structure, the structure of electrons in the outer shell of atoms and to give the eyes a sense of sight.
When light passes through a prism, light rays of different colors are deflected by different angular amounts. A prism separates the colors contained in the light falling on it. There are seven colors reflected by a prism. Red light deviates the least and violet light the most. Light of different colors also emerges from the prism in different paths. Hence, the colors are distinct and clear. Violet has a higher refractive index and red has a lower refractive index. When white light enters a prism, the refraction for different colors is also different. Therefore, the refractive index for different colors is also different.
$$\mathrm{Refractive\:index\:of\:violet\:\delta _{v}=(n_{v}-1)}$$
$$\mathrm{\delta _{v}-\delta _{r}=(n_{v}-n_{r})A}$$
The above equation is the difference between the refractive index of violet and red. The term $\mathrm{\delta _{v}-\delta _{r}}$ in the above equation gives the angular separation between the two boundary colors (violet and red) in the spectrum. This angle spectrum is called angular dispersion. The wavelength of the violet is 396.9 nm (approximately 400 nm). The frequency of violet is $\mathrm{7.5\times 10^{14}Hz}$.
Color Dispersion of Prism
Purple is not a natural spectral color. It is the mixture of red and blue which is used on the screens of television and computer. People may think violet and purple both are the same colors. But it is not true. Violet is the natural spectral color. The flower violet has the same color, so it is named violet. It can be separated from the other colors. But purple is a mixture of red and blue colors. So purple is a non-spectral color. Purple does not have a wavelength. Because it is a non-spectral color. Generally purple is a manmade color.
The color violet has many shades based on its usage and region.
Electric violet: This shade of violet is available in the middle spectrum on a computer screen. It is also called middle violet. If the wavelength of violet is between 380 to 420 nm. This shade is in the middle of this wavelength i.e. 400nm. Above 420 nm wavelength is considered to be Indigo color.
Vivid violet: It is the hue of violet. This shade color is parallel to violet by human visual. Vivid violet is also known as extreme violet. If the wavelength of violet is between 380 to 420 nm. This shade has a wavelength of 380nm. So it is called extreme violet.
Grape color: In ancient days grape is used as a color. But now it is not changed yet. The color of the grape is also a shade of violet. Now grape color is used in crayon colors. It is changed in 1994.
Color wheel violet: This shade of violet lies between magenta and blue in the RGB color wheel. It will appear in the chromaticity diagram with a wavelength of 417 nanometers. Near violet is the other name for this shade.
Purple is not a natural spectral color. It is a mixture of red and blue. There are many shades of purple is used and named in many regions. They are veronic, HTML (purple), Rebecca purple, and medium purple (X11).
Thistle: This shade of purple is from the Thistle plant. It is a light purple color that looks like that plant. In 1892 it was named a thistle color. This is the national flower of Scotland.
Orchid: In 1915 orchid is named color in English. It is a bright purple that resembles an orchid flower. The orchid flower is from the family of Ascocentrum pusillum and Laelia furfuracea.
Heliotrope: The color Heliotrope was named color in 1882. It is a vivid tone of purple. It resembles the heliotrope flower. This flower looks pink-purple.
Electromagnetic waves are waves that differ from mechanical waves and travel at the speed of light in a vacuum. The phenomenon of separation of colors in white light is called dispersion. The collection of these colors is called a spectrum. A good example of a color spectrum is the rainbow. The visible light spectrum is obtained from materials in a flammable state. And the agitated atoms in the gases emit visible light spectrums. The visible light is used to study the molecular structure, the structure of electrons in the outer shell of atoms and to give the eyes a sense of sight. A prism separates the colors contained in the light falling on it. There are seven colors reflected by a prism. Purple is not a natural spectral color. It is the mixture of red and blue which is used on the screens of television and computer.
Q1. What is Prism?
Ans. A prism is a solid material made of glass or plastic. A prism is formed by three nonparallel rectangular planes or faces. Out of these three faces, one face is made into a roughness. This is called the base of the prism. The other two faces are polished and these are called offset faces.
Q2. What are Fraunhofer lines?
Ans. A high number of dark lines are obtained in the analysis of the spectrum from the Sun. Fraunhofer lines are obtained from dark lines from the solar spectrum.
Q3. What are ultraviolet rays?
Ans. Ultraviolet rays come from the sun, electric arcs, and ionized gases. It has a low penetration capacity. The UV rays are absorbed by the ozone layer in the atmosphere. At the same time, it is harmful to the human body.
Q4. Define Interference
Ans. As two light waves converge or overlap each other; The phenomenon in which the light intensity increases at some points and decreases at other points is called the interference effect of light.
Q5. Define Emission and absorption spectra
Ans.
Emission Spectra − A spectrum obtained from a self-luminous source is a self-luminous emission spectrum. Each light source has a unique emission spectrum.
Absorption Spectra − The absorption spectrum is the spectrum obtained by passing light through an insulating material or medium. This spectrum has the properties of absorption objects.
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