Dispersion by a Prism – Class 12 | Chapter – 9 | Physics Short Notes Series PDF for NEET & JEE

Dispersion by a Prism: Dispersion by a prism refers to the phenomenon of light splitting into its component colors as it passes through a prism. When white light enters a prism, it bends or refracts as it passes through the prism due to the difference in the speed of light in air and the prism. The degree of bending or refraction depends on the wavelength of the light, with shorter wavelengths being refracted more than longer wavelengths.

As a result, the white light is separated into its constituent colors, forming a spectrum. The spectrum is a sequence of colors that ranges from red, which has the longest wavelength, to violet, which has the shortest wavelength. The order of colors in the spectrum is often remembered by the acronym ROYGBIV, which stands for red, orange, yellow, green, blue, indigo, and violet.

Dispersion by a Prism

The dispersion of light by a prism is an important phenomenon in optics and has many practical applications. For example, it is used in spectroscopy to analyze the composition of materials based on their spectral signatures. It is also used in the design of optical instruments such as cameras and telescopes, where the dispersion properties of lenses and prisms must be carefully considered to avoid chromatic aberration.

Dispersion by a Prism

  • When visible white light goes through a glass prism from one medium to another, distinct hues of light are refracted differently and exit the prism at different angles. It’s producing a rainbow-like effect, which is known as dispersion of light.
  • The phase velocity of a wave is affected by its frequency in this phenomenon.
  • From bottom to top, visible light is composed of seven colors: violet, indigo, blue, green, yellow, orange, and red.
  • Violet light is the most deviated of any color, whereas red light is the least distorted.
  • Prisms were used to split light into its constituents with varying polarizations or to reflect light.

Applications of Dispersion by a Prism

Dispersion by a prism has a wide range of applications in various fields, some of which are:

  • Spectroscopy: Spectroscopy is the study of the interaction of light with matter. The dispersion of light by a prism is an important tool in spectroscopy to study the composition of matter. By passing the light through a prism, it can be split into its constituent colors, and the resulting spectrum can be used to identify the elements or molecules present in a sample.
  • Photography: Prism-based cameras are used to split the light entering the camera into its component colors, which can be recorded separately. This technique is used to obtain high-quality color images in photography.
  • Optical Communications: In optical communications, dispersion by a prism is used to separate different wavelengths of light, which can then be used to transmit different signals. This technique is used in optical fiber communications, which is widely used for long-distance data transmission.
  • Astronomy: Dispersion by a prism is used in astronomy to study the light emitted by stars and galaxies. By analyzing the spectrum of light, astronomers can determine the chemical composition, temperature, and other properties of celestial objects.
  • Medicine: Dispersion by a prism is used in medical imaging to split the light emitted by a tissue or organ into its component colors. By analyzing the resulting spectrum, doctors can identify the presence of certain chemicals or molecules, which can aid in the diagnosis of diseases.
  • Art: Dispersion by a prism is used in art to create colorful displays. By projecting white light through a prism, artists can create a spectrum of colors, which can be used to create visually stunning displays.

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By Team Learning Mantras