Question

When divergence of volume charge density is zero?

Answer 1

Gives

Gauss law

$\nabla.E=-\frac{\rho}{\epsilon_0}$

$\rho=0$

$\nabla.E=0$

Volume charge density zero then

Divergence of electric field is zero

We know that continuity equation.

$\nabla.J=-\frac{d\rho}{dt}$

$\rho=0$

$\nabla.J=0$

Volume charge density zero then

Divergence of current density is zero