Define a wavefront. Use Huygens' geometrical construction to show the propagation of plane wavefront from a rarer medium (1) to a denser medium (2) undergoing refraction, hence derive Snell's law of

Question

Define a wavefront. Use Huygens' geometrical construction to show the propagation of plane wavefront from a rarer medium (1) to a denser medium (2) undergoing refraction, hence derive Snell's law of refraction.