To measure the amount of potential voltage that is available in a circuit, which instrument is used?

• A. Continuity tester
• B. Ohmmeter
• C. Voltmeter
• D. Ammeter

Answer: (C)

Measuring the potential difference, or the voltage available between two points, is done with a voltmeter. A voltmeter is connected in parallel across the points where you want to know the voltage, so it reads the difference in electric potential without drawing significant current from the circuit. It has a high input resistance to avoid loading the circuit and altering the voltage being measured.

Other instruments serve different purposes: an ammeter is placed in series to measure current, an ohmmeter measures resistance, and a continuity tester checks whether there is a complete conducting path. So for voltage, the voltmeter is the appropriate tool.