For a capacitor, if the potential difference between two stages is 1V when charging with 1V, the capacitance of this capacitor is 1F, that is, C=Q/U, but the capacitance is not determined by q or u, that is, C=εS/4πkd. Where ε is a constant, S is the relative area of the capacitor plates, D is the distance of the capacitor plates, and K is the electrostatic force constant. The capacitance of a common parallel plate capacitor is C=εS/d, (ε is the dielectric constant of the medium between plates, S is the plate area, and D is the distance between plates. )

The formula for calculating the potential energy of capacitor is e = Cu 2/2 = Qu/2.

Multi-capacitor parallel calculation formula: C=C 1+C2+C3+…+Cn.

Calculation formula of multiple capacitors in series:1/c =1/c1+1/C2+…+1/cn.

Multi-capacitors are added in parallel and series, and c = (c1* C2 * C3)/(c1+C2+C3).