Series and Parallel Circuits

Most basic electronic components (at least those with 2 terminals) can be connected in one of two ways: series and parallel. Series connections involve putting the components end to end so that they share a common node. Parallel means connecting the components so that they share two nodes (easy to visualize as side-by-side).

We can calculate the equivalent resistance of series resistors by adding their resistances: Req = R1 + R2 + R3 + …

For parallel, we can find the equivalent resistance by taking the reciprocal of the sum of reciprocal resistances: Req = 1 / (1/R1 + 1/R2 + 1/R3 + …)