Laws of refraction
The refracted plane wave front EF is constructed from the incident plane wavefront BD as follows :
(i) From B as the center draw an arc of a circle of radius
V2t, where t is the time taken by light to travel from D to E in medium :1, i.e. DE =
(ii) Draw tangent EF to this arc.
(iii) Then EF is the required refracted plane wavefront.
(iv) EG & parallel line BFH are refracted rays normal to
the refracted wavefront EF.
Thus, the laws of refraction are proved since the incident ray and the refracted ray lie on either sides
of the normal and they all lie in the same plane by the construction in the diagram.