# Electric Flux

1. Nov 23, 2014

### ewr

Why is the electric flux defined as (electric field) x (area), Φ = EA? How do you come up with that equation? Is it because the electric flux is proportional to the charge and surface area?

2. Nov 23, 2014

### Staff: Mentor

That's close, although it's not quite right to say that it's proportional to the charge; you can get the same amount of flux through a given surface with a small charge nearby or a larger charge farther away. That's why the field strength E appears in the formula.

3. Nov 24, 2014

Hence $dR = E.dS = Edscosx$