# How to use Gauss formula here?

1. Sep 12, 2005

### dreamfly

how －∫(v)laplace functor *J*dτ change into -∮(s) J(n) dS using Gauss formula?

2. Sep 12, 2005

### Galileo

Do you mean

$$\int_V \vec \nabla \cdot \vec J d\tau = \oint_S \vec J \cdot d\vec S$$
under the appropriate conditions on J, S and V.

This is the divergence theorem (also called Gauss' or Ostrogradsky's theorem). You cannot use Gauss' Law (if that is what you meant) to prove this. the divergence theorem is stronger and can be used to prove Gauss' law.

3. Sep 17, 2005

### dreamfly

ok thanks! it's just our teacher told us to prove this equation by Gauss' theorem.and now i've known the process.thanks!