Consider a static and azimuthally symmetric charge distribution (r) which produces no electric field outside itself except

Consider a static and azimuthally symmetric charge distribution ρ(r) which produces no electric field outside itself except a single, pure, spherical electric multipole field of order ℓ. Show that, when rotated rigidly about its symmetry axis with frequency ω, such a distribution generally produces a magnetic field outside of itself which is a superposition of two pure magnetic multipole fields, one of order l + 1 and one of order − 1.