CAPACITOR CIRCUITS IN SERIES, PARALLEL, & COMBO CIRCUITS

CAPACITORS IN SERIES CIRCUITS Rules for Series Circuits Current is the same for all parts of Circuit Charge is the same on all parts of Series Circuit Volts add in series V total = V 1 +V 2 +V 3 +… Resistors add in Series R total = R 1 +R 2 +R 3 +… Capacitors add inverses for inverse of answer

SOLVING CAPACITOR SERIES CIRCUITS Step 1: Solve for total capacitance Step 2: Solve for total charge Step 3: Solve for charge on each capacitor Step 4: Solve for voltage across each capacitor

CAPACITORS IN PARALLEL CIRCUITS Rules for Parallel Circuits Volts on each parallel branch are same Currents from each branch add to equal total from battery. I total = I 1 + I 2 + I 3 Charge from each branch adds Q total = Q 1 + Q 2 + Q 3 Capacitors add C total = C 1 + C 2 + C 3 Resistances add inverses

SOLVING CAPACITOR PARALLEL CIRCUITS Step 1: Solve for total capacitance. Step 2: Solve for total charge. Step 3: Solve for Volts on each branch. Step 4: Solve for charge on each branch. Step 5: Check to see if answers are consistent.

CAPACITORS IN COMBO CIRCUITS Find total capacitance Start in parallel section or most complicated section and work your way out applying the rules for series and parallel capacitors along the way. Use capacitance formula to solve for Q total. Apply rules for series and parallel from the battery outward using all forms of the capacitance equation.

SOLVING CAPACITOR COMBO CIRCUITS WHAT’S IN SERIES AND WHAT’S IN PARALLEL? Capacitors C2 and C3 are on parallel branches because the current from the battery splits before it gets to either of them. Capacitors C1 and C4 are each in series with the battery and the parallel group because all current from the battery must flow through them.

SOLVING CAPACITOR COMBO CIRCUITS FINDING TOTAL CAPACITANCE Start in the most complex area of the circuit and apply the series and parallel rules as you work outward toward the battery. In this case, start with finding the equivalent (total) Capacitance for the Parallel section, then add the resistors in series.

SOLVING CAPACITOR COMBO CIRCUITS FINDING TOTAL CHARGE & VOLTS FOR EACH PART Now find the total charge. Then, since volts add in series, you will need to find the voltages used by C1 & C4 and subtract them from the total provided by the battery to find the volts for the parallel branches.

SOLVING CAPACITOR COMBO CIRCUITS FINDING CHARGE ON PARALLEL CAPACITORS Finally, solve for charges Q2 & Q3 using the knowledge that Q=CV. Then check to see that the charges add up to the total as the rules for parallel state they should.