What is the term for the voltage measured across the terminals of a power supply?

The term for the voltage measured across the terminals of a power supply is called terminal potential difference. This is the voltage available to an external circuit, reflecting the energy per unit charge that can be delivered to loads connected to the power supply. It is significant in determining how much electrical work can be performed by the power supply.

When measuring the voltage at the terminals of a power supply, one is primarily concerned with the potential difference that is available to do work on a charge within the circuit. This is important because, in practical applications, the voltage can be affected by factors such as internal resistance within the power supply, the load connected to it, and overall circuit conditions.

Other terms mentioned, such as capacitance, are related to the ability of a capacitor to store charge, internal resistance pertains to the opposition within the power supply that reduces its output voltage under load, and rms voltage refers to the effective voltage of an alternating current (AC) source. None of these terms accurately describe the voltage directly available across the terminals of a power supply as terminal potential difference does.