# Electric Flux Density / Electric Field Intensity

Hey people,

I'm struggling to understand exactly what Electric Flux Density D and Electric Field Intensity E are.

So far, my understanding is that D depends on relative permittivity, while E depends only on the permittivity of free space. Also, I understand that D reflects only the free charges, while E reflects both free and bound charges. Where I'm stuck though, is that my book also tells me that D is independent of the medium it is in, while E is dependent on the medium it is in. This just doesn't click with me, since the actual value of E doesn't change if you change the medium (and thus the relative permittivity), while the value of D does.

Can anyone help me out here?

Last edited:

Born2bwire
$$\mathbf{D} = \epsilon \mathbf{E}$$