Which device is used to measure electrical resistance in a circuit?

• A. Ohmmeter.
• B. Ohm's law chart.
• C. Tachometer.
• D. Multimeter.

Answer: (A)

Measuring resistance involves determining how much a component resists current flow. An ohmmeter is designed for this task: it applies a small known current from its internal battery through the component and measures the resulting voltage drop to calculate resistance, showing the value directly. You typically use it with the circuit powered off to get an accurate reading and avoid damage. While a multimeter can measure resistance when set to the resistance function, the device specifically built to measure resistance is the ohmmeter. Tachometers measure rotational speed, and reference charts like an Ohm's law chart are tools, not measurement devices.