To complete the specification of the solution at any point , we need not only the amplitude, but also the phase. For waves traveling out in the radial direction away from the point source, we expect a form just like the string, , where is some phase. Given what we know of the amplitude from Eq. 3, the solution at any point at distance from the slit is then

Note that, we here have written the answer also in complex form, which describes simple harmonic oscillations of complex amplitude

This will be useful in future sections.

Thu Sep 13 15:26:14 EDT 2001