How is electric current measured within a circuit?

Electric current is measured using an ammeter, which is specifically designed for this purpose. An ammeter must be connected in series with the circuit to ensure that all the current flowing through the circuit also flows through the ammeter. This allows the device to accurately measure the amount of electric charge passing through it over a period of time, which is expressed in amperes (A).

In contrast, a voltmeter is used to measure voltage across two points in a circuit and is connected in parallel. A multimeter can indeed measure current, voltage, and resistance, but it must be set to the appropriate function for measuring current and can operate similarly to an ammeter when set accordingly. Lastly, a potentiometer measures voltage by comparing an unknown voltage to a known reference voltage but is not used directly to measure current. Understanding these distinctions highlights why the ammeter is the correct tool for measuring electric current.