An inverter is a device that converts direct current (DC) into alternating current (AC). It is commonly used in various electronic devices and systems where the primary power source is DC, such as batteries or solar panels, but the application requires AC power. Inverters are essential for many applications, including powering household appliances, electronics, and other devices that operate on AC power, even when the primary power source is DC.

A potentiometer is an instrument for measuring voltage by comparison of an unknown voltage with a known reference voltage.
The unknown voltage may be supplied by a standard cell or any other known voltage.
The potentiometer is extensively used for calibrations of voltmeter and ammeters and has, in fact, become the standard for the calibration of these instruments.