(i) State and explain Huygens Principle.Using it, obtain Snell's law of refraction.
(ii) When light travels from a rarer to a denser medium, the speed decreases. Does the reduction in speed imply a reduction in the energy carried by the light wave? 5mark
(i) Statement and explanation 1mark
Derivation of Snell's law 3mark
(ii) No. Energy carried by a wave depends on the amplitude of the wave, not on the speed of wave propagation. 1mark