1. Dec 14, 2007

lion8172

In the chapter on radiation (Chapter 11), Griffiths notes that an electric monopole does not radiate, but also that a point charge of electric dipole moment $$\mathbf{p} (t) = q \mathbf{d} (t)$$ (where $$\mathbf{d} (t)$$ is the instantaneous coordinate of the charge with respect to a fixed origin ) radiates with power
$$P = \mu_0 q^2 a^2/(6 \pi c)$$, where $$\mathbf{a}(t) = \ddot{\mathbf{p}} (t)$$. By "monopole," does he simply mean a point charge that doesn't move?

2. Dec 15, 2007

Shooting Star

That would be one case. Any distribution of charge which gives a spherically symmetric field outside of a certain region is an electric monopole.