Problem: (a) What is the capacitance of the 2 conductors +20nC and -20nC? (b) If the voltage difference between the 2 conductors increase to 250 V, then what else changes? a). I calculated that ΔV = 100 V. So then I plugged into the formula C = Q/ΔV. I thought 20 nC = 2 x 10^-8 C, which divided by 100 V = 2 x 10^-9C but the answer is 2 x 10^-10 C. What am I doing wrong? I know this is very simple but I have never studied physics before and am terrible at math. b). charge of the conductors increases to keep capacitance constant, since capacitance is a property of area and distance between plates (I think this is right but please tell me if it's wrong!) Thanks in advance!