In an electron diffraction experiment, consider a screen with asingle vertical slit of finite width d in the x-direction,"illuminated" from behind by a plane monochromatic electron wave ofwavelength λ with the wave fronts parallel to the plane of theslit (i.e, the wave is propogating perpendicularly to thescreen). Presume that we take the simple Huygen's principlemodel of diffraction and model the slit as a source of aspherically expanding (complex) wave (and, hence, each verticalline in the slit is a source of a circularly expanding wave).

Find an approximate analytic expression for the form of the waveamplitude (by "form" we mean here that you may neglect any constantfactor multiplying the wave amplitude) at a plane a distancez0 from the screen (assuming z0 d).