What defines a series circuit?

A series circuit is characterized by having all components connected in a single path, which means that the current flowing through the circuit is the same at every point along that path. This uniformity of current is a fundamental principle of series circuits, making it easy to analyze their behavior when additional components are added.

In such a circuit, the total resistance is simply the sum of the individual resistances of each component. Because there is only one path for the current to travel, the same amount of current flows through each component—leading to a situation where if one component fails or is removed, the entire circuit is interrupted, and current stops flowing.

This understanding underlies why current remains constant throughout a series circuit, while voltage can vary across individual components depending on their resistance.