# What exactly is Electric Flux Density?

1. Oct 8, 2012

### iVenky

We define flux density as D= ε E right?
or even ∇.D=ρ

But I can't link the above with what is given in the wiki where they have used the symbol "phi"

http://en.wikipedia.org/wiki/Electric_flux

What is the difference between D and symbol "phi"?

I would be really happy if you could help me as I am new to EMF.

Thanks a lot. :)

2. Oct 8, 2012

### Muphrid

$D$ and $\Phi$ are nothing alike, don't have the same units, don't represent different aspects of the same quantity, nothing. That they share the words "electric flux" in them is simply misleading, but the roots of this terminology are historical, I'm sure.

3. Oct 8, 2012

### iVenky

What I read was D is the no of electric lines which seems to be same as $\phi$. What is the exact physical meaning of D ?

Thanks a lot.