TestOut LabSim A+ Certification 2025 – 400 Free Practice Questions to Pass the Exam

The main function of a multimeter when testing a power supply is to measure voltage. This is crucial because the output voltage of a power supply must be verified to ensure that it is within the specified range for the devices it powers. Voltage measurement helps in diagnosing whether a power supply is functioning correctly or if it is providing the correct output required by the circuit or devices.

While a multimeter can indeed measure current and resistance, the primary objective when assessing a power supply is to check the voltage levels, as undervoltage or overvoltage can lead to damage or failure of electronic components. Measuring current or resistance can be useful in specific scenarios, but those are secondary functions when verifying the proper operation of a power supply. Additionally, measuring frequency is not typically relevant in the context of testing a standard DC or AC power supply, making voltage measurement the most significant function in this scenario.