Assertion: white light is dispersed into its 7 colour components by a prism.
Reason: different colours of light bend through different angles with respect to the incident ray as they pass through a prism.

Dear student, Both A and R are right, R is the correct explanation of A. Different colours of light bend through different angles because of difference among their wavelength due to which their speed differs in different medium and reaches the surface of material at different time. Regards