- #1
Hypercube
- 62
- 36
In his book on EM, Griffiths states:
Formally, electro/magnetostatics is the régime $$\frac{\partial \rho}{\partial t}=0, \hspace{0.25in} \frac{\partial \vec{\boldsymbol{J}}}{\partial t}=\boldsymbol{0}$$
He explains how in electrostatics charges do not move, or (more specifically), charge density does not change. It must remain fixed. I understand that. Second equation is regarding magnetostatics, which also makes sense. But then (few paragraphs down) he says:
More generally, since ##\frac{\partial \rho}{\partial t}=0## in magnetostatics...
Wait. I thought the first of the two equation applies to electrostatics, and the second one to magnetostatics?
So my question essentially comes down to which one(s) of the above equations applies to electrostatics and which one(s) to magnetostatics. Thank you.
Formally, electro/magnetostatics is the régime $$\frac{\partial \rho}{\partial t}=0, \hspace{0.25in} \frac{\partial \vec{\boldsymbol{J}}}{\partial t}=\boldsymbol{0}$$
He explains how in electrostatics charges do not move, or (more specifically), charge density does not change. It must remain fixed. I understand that. Second equation is regarding magnetostatics, which also makes sense. But then (few paragraphs down) he says:
More generally, since ##\frac{\partial \rho}{\partial t}=0## in magnetostatics...
Wait. I thought the first of the two equation applies to electrostatics, and the second one to magnetostatics?
So my question essentially comes down to which one(s) of the above equations applies to electrostatics and which one(s) to magnetostatics. Thank you.