A square filamentary differential current loop, dL on a side, is centered at the origin in the z = 0 plane in free space. The current I flows generally in the a_Ï•direction.

(a) Assuming that r >> dL, and following a method similar to that in Section 4.7, show that

(b) Show that

The square loop is one form of a magnetic dipole.

ol (dL)? sin@ 4r2 dA = a, I(dL)? dH = (2 cos e a, + sin 0 ag) %3D 43