a)

(i) What is meant by dispersion of light? 

(ii) Which color deviates least and the one which deviates most while passing through a glass prism?

                                                                                                                      OR

b) Explain the term scattering of light with the help of an example.

a)

(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).

                                                                                                 OR

b) 

The phenomenon of change in the direction of propagation of light caused by a large number of particles present in the atmosphere is called scattering of light. 

Example: The path of a beam of light becomes visible through a colloidal solution due to the scattering of light.