Resistors in Series and Parallel

The total resistance in the circuit with resistors connected in series is equal to the sum of the individual resistances.

The total resistance in a parallel circuit is equal to the sum of the inverse of each individual resistances.

A combination circuit can be broken up into similar parts that are either series or parallel.

When voltage sources are connected in series, their emfs and internal resistances are additive; in parallel, they stay the same.

The output, or terminal voltage of a voltage source such as a battery, depends on its electromotive force and its internal resistance.