Which component is essential for measuring voltage in an electric circuit?

To measure voltage in an electric circuit, a voltmeter is the essential tool. The voltmeter is designed specifically to measure electric potential difference between two points in a circuit. It is connected in parallel with the component across which the voltage is to be measured, ensuring that it can accurately capture the potential difference without significantly altering the current flowing through the circuit.

This functionality is critical because the voltmeter utilizes a high resistance in its design, which prevents it from drawing a significant amount of current. This characteristic allows it to provide an accurate reading of voltage without affecting the overall operation of the circuit being tested.

Other components mentioned, such as a resistor or an ammeter, serve different purposes. A resistor controls current flow, while an ammeter measures the current passing through a circuit. An inductor, on the other hand, stores energy in a magnetic field when electrical current passes through it. None of these components are designed specifically to measure voltage, which is why the voltmeter stands out as the necessary instrument for that task.