Question

Define the term 'wavefront of light'. A plane wavefront AB propagating from a denser medium (1) into a rarer medium (2) is incident of the surface P₁P₂ separating the two media as shown in fig.
Using Huygen's principle, draw the secondary wavelets and obtain the refracted wavefront in the diagram.

Answer 1

It is defined as the locus of all the particles of a medium vibrating in the same phase at a given instant of time.