(i) What is meant by dispersion of light?
(ii) Which colour deviates least and the one which deviates most while passing through a glass prism?

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Detailed Solution

(i) When white light is passed through a glass prism, it splits into its spectrum of colours (in order violet, indigo, blue, green, yellow, orange and red) and this process of white light splitting into its constituent colours is termed as dispersion.

(ii) Light undergoes refraction when it enters the prism obliquely. The extent of deviation depends on the wavelength. Therefore different colours undergo deviations at different angles and get separated. Light with the smallest wavelength deviates the most, and the one with the larger wavelength deviates the least, as shown in the figure below.

Among the 7 constituent colours of light, violet light has the least wavelength; hence, it deviates the most, and red light having the largest wavelength, deviates the least. Hence, the required order is violet, indigo, blue, green, yellow, orange, and red (VIBGYOR).

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