Prism is made by cutting glass or other transparent materials with precise angles. The prism is used for reflecting and analysing light. The prism splits the white light into constituent colours. 


When white light is passed through the prism, each of the constituent colours is bent at different angles. Violet light has the shortest wavelength, and it gets bent the most, and the red light with the longest wavelength gets bent the least. The prism is used in spectroscopes for analysing the nature of light and for understanding the structure and identity of the materials that emit and absorb light. The prism is generally made in the shape of a triangle. However, based on the application, the prisms are made in different shapes and forms. For example, the Nicol prism consists of two cut pieces of prism which are bonded together with Canada balsam. Nicol prism is used to produce plane polarised light from ordinary light. The Porro prism is used in periscopes, binoculars and monoculars since it consists of two prisms that produce reverse and inverted images. 

Dispersion through a Prism

Light of all wavelengths travels with the same speed in vacuum and air. However, the constituent colours in white light will travel at different speeds in the material medium of the prism. As a result,  the refractive index of the material of the prism will be different for different wavelengths of light. Therefore, the angles of refraction are different for different colours. They are said to exhibit dispersion. So, different colours in the incident beam emerge from the prism in different directions. This accounts for dispersion produced by a prism.  A medium in which the speed of light varies with wavelength is called the dispersive medium. The phenomenon of splitting the ray of white light into its constituent colours is known as dispersion. 

Electrostatic Shielding

When the effect of the electric field is blocked by the Faraday cage, it is called electrostatic shielding. The Faraday cage used in shielding is a closed chamber made from conducting material. This cage will block the external static and non-static electric fields. The cage will not block slowly varying magnetic fields such as the magnetic field due to Earth. The cage that can block the external magnetic radiation from the interior of the mesh should be smaller than the wavelength of the radiation, and the shield must be sufficiently thick. 

When the external electric field acts on a Faraday cage, the charges present within the cage will rearrange themselves to shield the interior from the external electric field. The action of the Faraday cage will depend on whether the cage is grounded or not. If the cage is not grounded, the interior wall will have a charge opposite to the exterior of the cage. As a result, the exterior wall of the cage will have a charge opposite the interior wall. However, If the cage is grounded, the excess charge on the exterior wall will go to the ground.  

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