A glass prism is a transparent object having two triangular ends and three rectangular sides. The refraction of light in glass is different from a glass slab. This is why in glass prism, the incident ray of light is not parallel to the emergent ray of light.
When a ray of light enters the glass it gets deviated two times First when it enters the glass prism and second when it comes out of the prism This is because the refracting surfaces of the prism are not parallel to each other. Also, when the ray of light passes through the prism it bends towards its base.
Dispersion of light
In 1665, Isaac Newton discovered that white light consists of seven colors. He found that if a beam of white light is passed through glass prism then it will split in to seven colors. These colors are red, orange, yellow, green, blue, indigo and violet (VIBGYOR).
Spectrum of white light: The band of seven colors formed when a beam of white light is passed through a glass.
Dispersion of light: The splitting of white light in seven colors is passing through a transparent medium.
The dispersion of white light occurs as the angle of refraction of different colors For example, red color deviates the least and is formed on the upper part of the spectrum and the violet color is deviated and is formed at the bottom of the spectrum.
The rainbow
Rainbow is formed when it is raining at the time of sunshine. When the white sunlight falls on the raindrops and leaves them, then the white light is refracted and an arc of seven colors is in the sky. In this situation, tiny raindrops act as glass.
Tyndall effect
When light is scattered due to particles in its path, it is called Tyndall effect. The way a beam of sunlight becomes visible when it passes through the dust particles in a room, when sunlight passes through a canopy of dense forest, are examples of Tyndall effect.
In 1859, Tyndall discovered that when white light is passed through clear liquid having small suspended particles, then the blue color of white light has shorter wavelength and scattered more than the red color that has long wavelength.
