What is an ohm meter used for?

• A. To measure current
• B. To measure resistance
• C. To measure power
• D. To measure voltage

Answer: (B)

An ohm meter is used to measure resistance. It uses its own internal battery to apply a small current (or voltage) to the component and then measures the response, displaying the resistance value based on Ohm’s law (R = V/I). This is different from measuring current, voltage, or power, which are done with ammeters, voltmeters, or wattmeters, respectively. For accurate readings, test when the circuit is de-energized and the component is isolated; testing in a live circuit can give incorrect readings or damage the meter. A near-zero reading suggests a short, a very high or infinite reading indicates an open circuit, and a reasonable finite value confirms the component’s resistance.