Series vs Parallel Circuits

Both with a 12V battery and 3 lights with 5 ohms of resistance Series Parallel

Voltage in Circuits In a series circuit, voltage is shared throughout the circuit. VT = V1 + V2 + V3 + … + Vn In a parallel circuit, voltage is the same everywhere in the circuit. VT = V1 = V2 = V3 … = Vn

Series Parallel

Current in Circuits In a series circuit, current is the same everywhere. This is because there is only one path for the electricity to flow through. IT = I1 = I2 = I3=…= In In a parallel circuit, the current that leaves the battery is divided by each path, with paths that have less resistance having more current. IT = I1 + I2 + I3+…+ In

Resistance in Circuits In a series circuit, the total resistance is the sum of all of the resistances added together. RT = R1 + R2 + R3 + … + Rn In a parallel circuit, the total resistance is the sum of the reciprocals of the resistance. 1/RT = 1/R1 + 1/R2 + 1/R3 + … 1/Rn (Careful when solving for this. Remember, you are solving for RT , not 1/RT)

Summary of Formulas Series Circuit Parallel Circuit Voltage VT = V1 + V2 + V3 + … + Vn VT = V1 = V2 = V3 = … = Vn Current IT = I1 = I2 = I3=…= In IT = I1 + I2 + I3+…+ In Resistance RT = R1 + R2 + R3 + … + Rn 1/RT = 1/R1 + 1/R2 + 1/R3 + … 1/Rn

Sample Question – Series Circuit

Sample Question – Parallel Circuit Calculate R3 and the current through the 12 ohm resistor

Practice problems are posted on the website!