# How to find electric-charge density distribution

1. Sep 14, 2013

### smantics

Given only an uniform electric field with unit vectors in the x, y, and z directions, how would you go about calculating the electric-charge density distribution p(r) for that electric field?

2. Sep 14, 2013

### Jolb

One nice formula you might try applying is one of Maxwell's equations: $$\nabla \cdot \mathbf{E} = \frac {\rho} {\varepsilon_0}$$ The symbol $\rho$ is the charge density that generates the electric field $\mathbf{E}$, and $\varepsilon_0$ is a proportionality constant called the permittivity of free space.

3. Sep 14, 2013

### smantics

Thanks, I will try that.

4. Sep 15, 2013

### mikeph

The divergence of a uniform field is zero. There are no charges, at least where the field is uniform.