1. The problem statement, all variables and given/known data Estimate the required radius of each plate. The plates are separated in air by 0.01mm and has a capacitance of 400pF. There are 4 pairs of plates. 2. Relevant equations c= εrε0*A(n-1)/ d 3. The attempt at a solution Find area. Transposing for A A = dc/εrεo A= 1*10^-5*400*10^-12/1*8.85*10^-12*7 I am getting 6.457^-27mm. I am going wrong somewhere, pretty sure the equation is correct though.