A narrow beam of white light is shown to pass through a triangular glass prism. After passing through the prism, it produces a specturm XY on a screen.
(a) State the colour seen at `X and Y`.
(b) Why do different colours of white light bend through different angles with respect to the incident beam of light ?
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Explanation

(i) Violet colour bends the most and red colour bends the least on passing through glass prism.
(ii) The cause of dispersion is that different is that different colours of white light having different wavelengths deviate through different angles on passing through the prism. That is why they appear split on coming out from the prism.
(ii) Rainbow is the best example of dispersion of sunlight in nature.
(iv) The phenomenon of dispersion teaches us universal brotherhood. There is such a huge variety of people in the universe. They are constituents of one family, i.e., God's family. There should be no distinction on the basis of colour, cast, crees, religion and so on. As we are part of one family, we should live like brothers with no hatred or violence against one another.