# Difference Between Bound and Free charge

1. Oct 8, 2012

### rshalloo

1. The problem statement, all variables and given/known data

So I'm having a bit of trouble getting my head around this concept and was hoping someone would be able to shed some light on it.
I know the definition. i.e free charge isn't bound to a nucleus whereas bound is. But physically what difference does this make. i.e are free charges only found on conductors, or are the chagres that I would have started learning electrostatics with (griffiths 2-3) free charges aswell?

2. Relevant equations

D = ε_0 E + P

3. The attempt at a solution

I would say that yes the original charges are free and that bound charges only exist in dielectrics but I'm not sure if this is the right approach.

Thanks

2. Oct 8, 2012

### voko

Free charges are not necessarily found in conductors only. They may also exist, for example, in vacuum. "Free" really means just that the charge can move freely. And this division is not absolute: any bound charge becomes free if you make it subject to a sufficiently strong electric field - stronger, in fact, than the fields that make it "bound".