Series and Parallel

a single resistance that can replace all the resistances in an electrical circuit while maintaining the same current when connected to the same source

symbol Rtotal or Rt

by combining KVL, KCL and Ohm’s Law, the following rules can be derived:

for any number of resistors connected in series

Rt = R1 + R2 + R3

for any number of resistor connected in parallel

1/Rt = 1/R1 + 1/R2 +1/R3

Calculate the equivalent resistance in a series circuit containing the following resistances in series: 26 Ω, 11 Ω and 18 Ω.

55 Ω

Calculate the equivalent resistance of a circuit with the following resistors in parallel: 5 Ω, 10 Ω and 30 Ω.

3 Ω

Find the equivalent resistance in the circuits below:

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