# EL ENG 16A Lecture Notes - Lecture 5: Voltage Source, Short Circuit, Farad

## Document Summary

The equivalent charge is not always possible to find. If capacitors in the circuit are initially charged (with different amounts of charge), then we cannot use equivalence formulas. Capacitors in series always have the same amount of charge, but if two capacitors in series are initially charged, then they possibly have different amounts of charge on them. Therefore, we cannot combine the two series capacitors into one equivalent capacitance using the series equivalence equation for capacitors. Therefore, we cannot find the equivalent charge between thetwo terminals. The derivation of the equivalence equation for series capacitors assumes that the charge on each series capacitor is the same. Although the capacitors look like they are in series, because they have different initial charges, the equivalence formula does not apply capacitance - represents how much charge can be stored for a given amount of voltage. The more charge that is put on the capacitor, the higher the voltage will be.