Glass Prism-Dispersion of White Light, Typical Materials Include Glass, Plastic, and Fluorite (For CBSE, ICSE, IAS, NET, NRA 2022)

Glide to success with Doorsteptutor material for competitive exams : get questions, notes, tests, video lectures and more- for all subjects of your exam.

Glass Prism - Dispersion of White Light

About Prism

  • An Optical Prism is a Transparent Optical Element with Flat, Polished Surfaces That Refract Light.
  • At Least One Surface Must Be Angled — Elements with Two Parallel Surfaces Are Not Prisms.
  • Some Types of Optical Prism Are Not in Fact in the Shape of Geometric Prisms. Prisms Can Be Made from Any Material That is Transparent to the Wavelengths for Which They Are Designed.

Typical Materials Include Glass, Plastic, and Fluorite


A Prism is Defined as a Transparent Solid Body
  • A Prism is Defined as a Transparent Solid Body That Has Three Rectangular Lateral Surfaces and Two Triangular Faces That Are Inclined at an Angle.
  • The Angle at Which the Surfaces Are Inclined is Known as the Angle of the Prism Which is Also Known as Refracting Angle.
  • The Other Important Term in the Prism is the Angle of Deviation of a Prism. It is Defined as the Angle between the Incident Ray and the Emergent Ray.

Calculation of Deviation Angle

Calculation of Deviation Angle

The Deviation Angle Depends on Wavelength Through N, so for a Thin Prism the Deviation Angle Varies with Wavelength According to

About Dispersion

Dispersion is defined as the separation of white light into different colors when the light is passed through the prism.

Dispersion of Light

Dispersion of Light
  • The scattering of light depends on the wavelength of the light.
  • So, it can be said that the degrees of deviation are dependent on the wavelengths.
  • The deviation in the path of the light is inversely proportional to the wavelength.
  • White light is primarily composed of light of different wavelengths (colors) that are violet, indigo, blue, green, yellow, and red with red having the highest wavelength while the violet having the lowest wavelength.
  • Red light suffers the least amount of deviation and violet the most.
  • All the wavelengths suffer different angles of deviation, when white light passes from one optical medium to another, different colors of light split and this phenomenon of splitting of light into its components as result refraction is called dispersion.

Dispersion of White Light by a Glass Prism

  • When white light is made to pass through a prism, a spectrum of seven colors is formed which shows that white light is a mixture of seven different colors.
  • Prism only acts as a medium for the separation of the seven colors. When light falls on the glass prism, refraction takes place.
  • Hence, the wavelength of different components of light is different and the frequency is constant, each component gets deviated by a different angle due to the difference in velocity in the glass medium.
  • Red color having the maximum wavelength deviates the least and forms the upper part of the spectrum whereas violet having the least wavelength deviates the most.

Developed by: