1. The problem statement, all variables and given/known data The space between the plates of a plane capacitor is filled with a dielectric of constant k. The plate gets a charge of surface density L_0 . Determine the force per unit area that is exerted by the field on the dielectric. 2. The attempt at a solution I found the bound charge density which came out to be L = L_0(1 -1/k) Now I know the E inside the plates(without dielectric) is L_0/epsilon_0 and the field due to the induced charge of one side is L/2 epsilon_0 in the opposite direction . So I found net E(by superposition principle) , and multiplied by L i.e. charge per unit area. But this doesnt match the answer.