Read the passage and answer the question given below <br><br>
The phenomenon of splitting of which light into its component colour on passing through a refraction medium such as a glass prism is called dispersion of light. The pattern obtained on the screen is called spectrum. <br><br>
Cause for dispersion of light: Light rays of different colours travel with the same speed in vaccum. But in a refracting media like glass, water etc; light of different colours travel with different speeds. The speed of violet colour is the least while the speed of the red is the largest in glass. Hence the violet colour is deviate the most and the red colour the least. The other colours indigo, blue, green, yellow and orange are deviated by intermediate angle. <br><br>
Question : Dispersion of light through a medium is due to
