# Why the electric field around a positive charge is always directed away from it?

1. Aug 3, 2015

### Sharvina Gungah

Hello everyone!
My question is: why the electric field around a positive charge is always directed away from it? and why not towards?

2. Aug 3, 2015

### stedwards

Gauss Law says the electric field is directed away from a positive charge. $\nabla E=\rho$
The sign is convention. Gauss Law could have been, $\nabla E=-\rho$, and with changes of sign made to $\rho$ and $J$ in the rest of Maxwell's equations and the Lorentz equation of electromagnetic force, it would be just as useful.

Last edited: Aug 3, 2015
3. Aug 3, 2015

### fireflies

Because it is repulsion.

The gravitational field is measured by keeping a unit positive charge in the field. The positive-positive repulsion makes the force away from it.

4. Aug 3, 2015

### CWatters

A repulsive gravitational field could be very useful :-)

5. Aug 3, 2015

### Staff: Mentor

That's not correct. The direction of the field is completely arbitrary. We denote it as being directed away from positive charges simply because of convention.

6. Aug 3, 2015

### fireflies

Yes, because of convention. I mentioned that in this statement

Maybe I should have added that the measurement is done in the direction the unit positive charge (point charge in fact) moves. I meant by "Measurement done"=how we measure it (conventionally)

7. Aug 5, 2015

### Qwertywerty

Convention . You could consider - we draw electric field lines moving away from +ve charges , and moving towards -ve charges - as given by Faraday .

This is simply convention .