Question

What gives the new position of a wavefront at a later time in Huygens' construction?

Options

• A line drawn through the centre of every sphere

• The amplitude of the wavelets in the backward direction

• A common tangent drawn to all the spheres

• The original wavefront at the earlier time

Answer 1

A common tangent drawn to the spheres formed by secondary wavelets gives the new wavefront. This locates the wavefront at a later time.