What device is used to measure the resistance of a circuit?

The device specifically designed to measure the resistance of a circuit is the ohmmeter. It operates by applying a small voltage across the resistance and measuring the resulting current that flows through it. This process allows the ohmmeter to calculate the resistance using Ohm's law, which states that resistance is equal to voltage divided by current (R = V/I).

An ohmmeter is essential in troubleshooting and testing electrical components, ensuring that they function correctly by confirming that their resistance values are within specified limits. While a multimeter can also measure resistance along with other electrical parameters, the core function of an ohmmeter is dedicated solely to resistance measurement, making it the most accurate choice for this specific task. In contrast, devices like ammeters and voltmeters serve entirely different purposes—measuring current and voltage, respectively—so they do not apply in this context.