Resistance in Series and Parallel
Series Equivalent Resistance: Rt = R1 + R2 + R3 equivalent resistance of loads in series found by adding up the resistance of the individual loads Rt = R1 + R2 + R3 Current decreases as more loads are added Voltage in each load decreases as more loads are added so individual resistance can stay constant.
Parallel Equivalent Resistance 1/Rt = 1/R1 + 1/ R2 + 1/R3 equivalent resistance of loads in parallel is lower than the resistance of any of the individual loads. It is calculated as: 1/Rt = 1/R1 + 1/ R2 + 1/R3 Voltage of each load is the same as the sources Current stays constant
Eg) If 3 resistors are connected in a parallel circuit, determine the total resistance. Resistor 1 is 2 ohms, resistor 2 is 4 ohms and resistor 3 is 6 ohms. 1/Rt = 1/R1 + 1/ R2 + 1/R3 1/Rt = 1 /2 + ¼ + 1/6 1/Rt = 6/12 + 3 /12 + 2/12 1/Rt = 11/12 Rt = 12/11 Rt = 1.09ohms