Which device is used to measure electrical resistance?

Which device is used to measure electrical resistance?

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

Answer: (C)

Measuring electrical resistance requires a device that can determine how much a component resists current. That device is an ohmmeter. An ohmmeter sends a small, known current through the component and measures the resulting voltage, or it applies a known voltage and measures the current, then calculates resistance using Ohm’s law (R = V/I). This direct resistance reading is what makes it different from meters that only measure voltage or current. An ammeter measures current, a voltmeter measures voltage, and a galvanometer detects small currents or voltages but does not provide a direct resistance value. In practical HVAC work, you use an ohmmeter to check the resistance of sensors, heating elements, or motor windings, making sure the circuit is de-energized before testing.

Measuring electrical resistance requires a device that can determine how much a component resists current. That device is an ohmmeter. An ohmmeter sends a small, known current through the component and measures the resulting voltage, or it applies a known voltage and measures the current, then calculates resistance using Ohm’s law (R = V/I). This direct resistance reading is what makes it different from meters that only measure voltage or current. An ammeter measures current, a voltmeter measures voltage, and a galvanometer detects small currents or voltages but does not provide a direct resistance value. In practical HVAC work, you use an ohmmeter to check the resistance of sensors, heating elements, or motor windings, making sure the circuit is de-energized before testing.