Which instrument is used to indicate the potential difference between two points in a circuit?

The instrument specifically used to measure the potential difference, or voltage, between two points in an electrical circuit is the voltmeter. A voltmeter is designed to be connected in parallel with the component or section of the circuit where the voltage measurement is desired. It provides a clear reading of the voltage present, allowing technicians to determine whether a circuit is operating within expected parameters.

In contrast, while a multimeter can also measure voltage (along with other electrical properties such as current and resistance), it is not dedicated solely to that purpose. An ammeter measures current, which is the flow of electric charge through a circuit, and an ohmmeter is used specifically to measure resistance within a circuit. Therefore, the voltmeter is the most direct answer for indicating the potential difference in a circuit.