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

• A. Voltmeter
• B. Ammeter
• C. Ohmmeter
• D. Wattmeter

Answer: (A)

Measuring the electrical potential difference between two points is about reading voltage. A voltmeter is designed for that purpose. It’s connected across the two points (in parallel) so it detects the difference without forcing current through the circuit. Its high internal resistance minimizes loading the circuit, keeping the measurement accurate, and the result is read in volts. Other instruments measure different things: an ammeter measures current and is placed in series, an ohmmeter measures resistance (usually with the circuit off), and a wattmeter measures power (P = V × I). So the instrument that measures potential difference between two points is the voltmeter.