1. The problem statement, all variables and given/known data a parallel plate capacitor has 2 plates separated by a dielectric of rel. permittivity 5.0 are separated by 0.20mm and have area of 5.0 cm2. Potential difference between the plates is 500V. I need to be able to calculate the free surface charge density. 2. Relevant equations I'm assuming Dout = Din From boundary conditions D1 ┴ = D2 ┴ and D2 ┴ - D1 ┴ = σf Could someone just confirm what the boundary conditions are so I can say that the free surface charge density is zero or not! 3. The attempt at a solution I have Dout = Din = ε0Ein + P so from calculations P = 4.43x10-9 - (8.85x10-12 x 100) P = 3.54x10-9 Cm-2 Could I just say; D1 ┴ = D2 ┴ so there is zero free surface charge density!