Series Circuit Series Circuit in which current passes

Series Circuit

Series Circuit in which current passes through all resistors Only one path for current Each resistor uses up some of the potential Vsource = Va + Vb +. .

Resistance Equivalent resistance for devices in a series circuit is sum of individual resistances R = R 1 + R 2 + R 3 + …

Current in a series circuit is the source voltage divided by the equivalent resistance Current is the same everywhere in the circuit Icircuit = Vsource/Req

Example Two resistors, 47Ω and 82Ω, are connected in series across a 45 V battery. What is the current in the circuit? What is the voltage drop at each resistor? Known: R 1=47Ω R 2=82Ω V=45 V Req = R 1 + R 2 Req = 47Ω + 82Ω = 129Ω

Example Continued Current in the resistor: I = V/R I = 45 V/129Ω = 0. 349 A

Example Continued Will current increase, decrease or stay the same if the 47Ω resistor is replaced by a 37Ω resistor? New Req = 37Ω + 82Ω = 119 Ω I = V/R = 45 V/119Ω = 0. 378 A Current increases

Parallel Circuits

Parallel Circuit Multiple pathways for current Total current is the sum of the currents at each resistor (Current is NOT the same everywhere) Potential difference is the same everywhere in the circuit

Parallel Circuit Placing resistors in parallel always decreases the equivalent resistance of the circuit BUT. . . This increases the current!

Symbols Used

Sample Circuits Circuit A Circuit B