Which of the following meters must use internal power to check a load or circuit?

The correct answer is that an ohmmeter must use internal power to check a load or circuit. An ohmmeter measures resistance by supplying a small amount of current through the resistor or component being tested. This internal power is necessary for the meter to calculate the resistance based on the voltage drop across the component.

In contrast, a voltmeter measures the potential difference between two points in a circuit and typically does not require internal power to function when used under normal conditions. It measures voltage without drawing significant current from the circuit. An ammeter measures current flow and is designed to be connected in series in a circuit, which allows it to measure the current directly without needing external power. A multimeter can measure voltage, current, and resistance, but when measuring voltage and current, it does not require internal power.

Understanding the function of each type of meter helps clarify why the ohmmeter needs internal power; it is fundamentally linked to how resistance is measured in electrical circuits.