The backwave D1D2 does not exist FIGURE 10 1 (b) At a
large distance from
the source, a small
portion of the
spherical wave can
be approximated by a
plane wave Rationalised 2023-24
Physics
258
Thus, if we wish to determine the shape of the wavefront at t = t, we
draw spheres of radius vt from each point on the spherical wavefront
where v represents the speed of the waves in the medium