Peoples Physics Concepts

15.3 Capacitors in Series and Parallel

15.3 Capacitors in Series and Parallel

• Apply the equations governing capacitors hooked up in series and parallel.

Students will understand and apply the equations governing capacitors hooked up in series and parallel.

Key Equations

Cparallel=C 1 +C 2 +C 3 +... [5] Capacitors in parallel add like resistors in series

1

Cseries

=

1

C 1

+

1

C 2

+

1

C 3

+... [6] Capacitors in series add like resistors in parallel

Guidance

Capacitors in parallel have the same voltage, but different charge stored. Capacitors in series have the same charge

stored, but different voltages. Remember that if a capacitor are hooked up to the battery they will have the same

voltage as the battery. If the capacitor is unhooked from a battery and other capacitors are attached to it, then the

voltage can change but the total amount of charge must remain constant. Charge conservation holds that charge can

not be created or destroyed. When solving problems involving capacitor circuits, we use the equation for the charge

on a capacitor much like we use Ohm’s Law.

Example 1

Two capacitors, one of 10;μF (C 1 ) and one of 60μF (C 2 ), are connected to a 10V battery in series. A diagram of the
circuit is shown below. Determine (a) the total capacitance, (b) the charge stored on the 100μF capacitor, and (c)
the voltage drop across the 60μF.