Poynting's Theorem in Griffiths' Electrodynamics

[Zubair Ahmad]

In Griffith's electrodynamics he writes about poynting's theorem.He considers some charge and current configuration. Then he says that these charges move.Which charges is he talking about and why would they move?

 

[Riotto]

What's your objection to moving charges? Currents are produced by moving charges. In general, a given charge can also accelerate due to the forces experienced by the electric and magnetic field produced by the other charges.

 

[Dale]

Which charges is he talking about and why would they move?

Any charges moving for any reason. It is a general proof.

 

[Zubair Ahmad]

Any charges moving for any reason. It is a general proof.

Ok the current density J which comes in proceeding steps is due to motion of these charges but when he uses ampere Maxwell law he relates it to same E and B which are due to some other source.