- #1
JD_PM
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In chapter 10 (Radiation; just after example 2 from 'Radiation from an arbitrary source') of Introduction to Electrodynamics by G. Griffiths he asserts that a charged sphere with oscillating radius doesn't radiate because, by Gauss law, ##E## stays the same no matter where the charges are located (either around a inner surface enclosed by a Gaussian sphere or the center of the Gaussian sphere):
$$\vec E = \frac{kQ}{r^2}\hat {r}$$
But I don't get it. If the sphere's radius is oscillating the picture I have in my mind is the charged ball kind of bouncing back and forth, which would mean that the sphere is being accelerated and thus it should radiate...
Why is Griffiths saying it will not radiate?
I think he is considering this case as that of an electric monopole, however that one shouldn't oscillate.
Thanks.
$$\vec E = \frac{kQ}{r^2}\hat {r}$$
But I don't get it. If the sphere's radius is oscillating the picture I have in my mind is the charged ball kind of bouncing back and forth, which would mean that the sphere is being accelerated and thus it should radiate...
Why is Griffiths saying it will not radiate?
I think he is considering this case as that of an electric monopole, however that one shouldn't oscillate.
Thanks.