What is the nature of the beam of light produced by a lighthouse?
(a) A beam of monochromatic light undergoes minimum deviation through an equiangular prism, how does the beam pass through the prism, with respect to its base ?
(b) If white light is used in same way as in part (a) above, what change do you expect in the emergent beam ?
(c) What conclusion do you draw about the nature of white light in part (b) ?