The electric field intensity in polystyrene (relative permittivity 2.55) filling the space between the plates of a parallel plate capacitor is 10kV/m. The distance between the plates is 1.5mm.
Calculate the surface charge density of free charge on the plates,
and the surface density of polarization charge
rho s = D dot an
The Attempt at a Solution
I am having a hard time seeing how the surface charge density equals the d field normal to the surface in this case?