A monochromatic plane wave with fields E₀ and B₀ scatters from a thin conducting disk of radius a. In the long-wavelength limit, the scattered field is described by electric and magnetic dipole radiation fields with moments

The unit vector n̂ points in the direction of the incident wave propagation vector when the latter is normal to the plane of the disk. Use Babinet’s principle to deduce the effective dipole moments which characterize the diffracted field when a circular hole of radius a in a flat conducting plane is illuminated by a plane wave with aperture fields E_a and B_a. Do not assume normal incidence for the diffraction problem.

Pa 16 -a x ( x Eo) 3 and md= 8 3 -a (. Bo).