# Conditions for a E field to be possible

1. Nov 23, 2013

### cutesteph

If I want to verify an electric field E is possible in free space, do I just need to check ∇xE =0?

2. Nov 23, 2013

### WannabeNewton

In free space what always has to hold is $\vec{\nabla}\cdot \vec{E} = 0$ whereas $\vec{\nabla}\times \vec{E} = 0$ only holds in electrostatic systems. Is your system electrostatic?

3. Nov 23, 2013

### cutesteph

Yes, the system is electrostatic.

4. Nov 23, 2013

### WannabeNewton

Then yes you have to check that the electric field is irrotational. You also have to check that it is divergence-free.