1. The problem statement, all variables and given/known data An air-filled spherical capacitor is constructed with inner and outer shell radii of 7.00 and 14.0 cm, respectively. (a) Calculate the capacitance of the device. (b) What potential difference between the spheres results in a charge of 4.00 microC on the capacitor? 2. Relevant equations C = ab / Ke(b-a) C = Q/V 3. The attempt at a solution (a) C = ab/Ke(b-a) = (.07m * .14m) / (8.9875*10^9N*m^2/C^2 * .07m) = 1.558*10^-11 (b) C = Q/V V = Q/C = (4*10^-6C) / (1.558*10^-11) = 2.56*10^17 Book's Answers: (a) 15.6 pF (b) 256 kV I'm pretty sure I messed up somewhere with units and converting, as I'm not sure what units I ended up with, and these answers are much bigger than the book answers. I'm not sure where I went wrong though.