Which instrument is used to measure resistance in a circuit?

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

Answer: (C)

Measuring resistance requires determining how much a component resists current flow. An ohmmeter is designed for this specific task: it applies a small test signal to the unknown resistance and measures the response to calculate and display the resistance in ohms. That’s why this instrument is used when you want to know how much a component or section of a circuit resists current.

Other instruments do different jobs. A voltmeter measures voltage and is placed across two points in parallel. An ammeter measures current and is placed in series with the circuit. A wattmeter measures power, requiring both voltage and current to calculate P = V × I. Because an ohmmeter generates its own test signal, resistance measurements should be made with the component isolated from power and other circuitry to avoid inaccurate readings or damaging the instrument.