When using a series circuit, what happens to the current when any device fails?

In a series circuit, all components are connected end-to-end, forming a single path for current to flow. If any device within this circuit fails—such as a bulb burning out or a switch opening—the electrical path is interrupted. This interruption means that the entire circuit becomes open, and as a result, current cannot flow through the circuit anymore.

This behavior is a fundamental characteristic of series circuits. When one component fails, the whole system is affected because there is no alternate route for the current to take. Consequently, all devices connected in series will stop working until the fault is resolved. Understanding how series circuits operate is essential for diagnosing electrical issues and ensuring proper repairs in oil heating systems and other applications where circuits are employed.