A device used to measure resistance is called an

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

Answer: (C)

Measuring resistance requires an instrument that can determine how much a component opposes current flow. An ohmmeter does exactly that: it applies a small test current (or voltage) and measures the resulting voltage (or current) to calculate resistance, then displays it in ohms. This uses Ohm's law: R = V / I. This is different from an ammeter, which measures current and is placed in series; a voltmeter, which measures voltage across a component; and a wattmeter, which measures power. For safe and accurate readings, ensure the circuit is de-energized and the component is isolated, because applying power or including other circuit paths can distort the reading.