![]() ![]() We should know that frequency is inversely proportional to the wavelength. All seven colours differ in their frequencies. Because of this Violet colour forms the lowermost part of the spectrum. On the other hand, violet is the colour in the spectrum of white light which has minimum speed in the glass prism hence it's the angle of deviation is the most. Out of the seven colours in the spectrum of white light red is the colour which has a maximum speed in the glass prism and hence it's the angle of deviation is the least Because of which red colour forms the upper part of the spectrum. All the different colours of light ray travel at different speeds in glass and so the angle of bending or angle of refraction of each light ray is different. The degree of refraction also can be said as the bending of each light ray depends upon their individual speed while passing through the prism. The basic reason behind the dispersion of white light into seven different colours is because all the seven rays of light of different colours travel at different speeds through the glass prism. So now we know about a lot of things about the dispersion of white light and it's time to know the reason behind the dispersion of white light by a glass prismĭispersion of White Light by a Glass Prism Red, Orange, Yellow, Green, Blue, Indigo and Violet and these seven colours are together denoted as a term called VIBGYOR where V denotes Violet I denotes Indigo B denotes Blue G denotes Green Y denotes Yellow O denotes Orange and R denotes Red. The Seven Colours in the Band Appearing on the White Screen are: ![]() The band of seven colours which is formed on a white screen when a beam of white light is passed through a transparent material like a glass prism is called a spectrum of white light. The prism’s refractive index for both blue and red colours. The value ( α o ) b − ( α o ) r is called the angular dispersion between the blue and the red rays. Where : ( n r ) is the prism’s refractive index for red light and ( n b ) is the prism’s refractive index for blue light. The angle of deviation of the blue light is estimated from the relation : The angle of deviation of the red light is estimated from the relation : The thin prism is always in the position of minimum deviation, It disperses the white light into the seven spectral colours, where : The angle of deviation is the angle between the line of the incident ray and the final refracted red ray.ĭeduction of angular dispersion in thin prism : The angle of dispersion is the angle between the red and blue rays after they have refracted through the prism. You can set the refractive index for red light (n r ) and the difference in indices for red and blue light (n b -n r ). Use the slider to change the initial angle of incidence. White light is incident on a 60°, 60°, 60° prism. Now we should know about the colours that are mixed to form the white light. This clearly shows us that the white light is made up of seven different colours which get separated when this white light is passed through any transparent surface like a glass prism. The splitting up of white light into seven different colours of the ray of light when passed through a prism is called dispersion of light. On entering the prism the white light splits into a broad patch of seven colours on a screen placed in front of the prism. In the above figure, we can clearly see a beam of white light is passed through a glass prism. Let’s start with a diagram of light dispersion in a prism, it will help us understand this phenomenon more clearly and precisely. Further, we will study what is dispersion, what is the prism, the reason behind the dispersion of white light, what colours are mixed to form a white light and so on. This led to the discovery of the fact that white light is actually a mixture of light of seven different colours. When he made a ray of white light pass through a glass prism of triangular shape, the white light split into a band of seven different colours on the white screen placed in front of the glass prism. ![]() Do you know the light that appears to us as white when seen through naked eyes is actually a mixture of seven different colours of light? This was first told by Newton after he performed an experiment with the glass prism. ![]()
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