Lesson 3: Reducing Simple Series-Parallel Combination Circuits Some people can look at this circuit and tell right away that the total resistance is given by: RT = R1 + R2 || R3   But it is also important to master the procedures for reducing the circuit, step-by-step, through a series of equivalent circuits.
 Example Suppose you are given this set of values: R1 = 1.3 MW R2 = 860 kW R3 = 1.0 MW Solution Plug the given values into the equation and solve for RT: RT = 1.3 MW + 860 kW || 1.0 MW RT = 1.3 MW + 462 kW RT = 1.76 MW But let's approach the problem in a slightly different way--one that will eventually make it possible for you to solve circuits that are far more complicated. Here is the combination circuit with values assigned to the resistors First combine the parallel resistors, R1 and R2, to form equivalent resistance R2, 3: Then combine the series resistors, R1 and R2, 3, to get the value for equivalent resistance R1, 2, 3: :Any resistor circuit can indeed be portrayed as a single resistor.