Circuits and Circuit Elements Resistors in Series and in parallel

Resistors in Series Series – describes a circuit or portion of a circuit that provides a single conducting path without junctions When resistors are arranged in series, the current flowing through each resistor is the same Equivalent resistance – the total resistance of a circuit

Resistors in Series

Resistors in Series For resistors in series, the equivalent resistance is equal to the sum of all of the resistors Req = R1 + R2 + R3… Total Potential difference (voltage) = Current * Equivalent Resistance VTot = IReq The equivalent resistance of a series combination of resistors is always greater than any individual resistance

Resistors in Series Potential difference across a given resistor can be calculated by multiplying the current (which is constant) by the resistance of the given resistor V1 = IR1 or V2 = IR2 In a series circuit, all of the elements must be able to conduct electrical charge If one bulb goes out or one wire gets disconnected, the entire circuit fails

Resistors in Series Resistors are placed in series to regulate current Able to combine several small resistances to get a large overall resistance May be a safety feature, such as in burglar alarms

Resistors in Parallel Parallel – describes two or more components in a circuit that are connected across common points or junctions, providing separate conducting paths for the current There is more than one pathway through the circuit or part of a circuit Resistors in parallel have the same potential difference across them V is constant The sum of the individual currents in parallel resistors equals the total current ITot = I1 + I2 + I3 …

Resistors in Parallel

Resistors in Parallel The equivalent resistance of resistors in parallel can be calculated using a reciprocal relationship 1/Req = 1/R1 + 1/R2 + 1/R3 … The equivalent resistance is always less than the smallest resistance in the group of resistors Parallel circuits do not require all elements to conduct The circuit will continue so long as there is at least one complete pathway from one terminal to the other

Resistors in Parallel