What is the primary function of a diode?

The primary function of a diode is to direct electrical power in one direction, which is fundamental to its operation. A diode is a semiconductor device that allows current to flow through it in one direction while blocking it in the opposite direction. This property enables diodes to be used in various applications, including rectification, where alternating current (AC) is converted to direct current (DC). The characteristic of a diode to prevent backflow of current is essential in protecting circuits and ensuring that electrical components receive power only in the intended direction.

In contrast, measuring voltage or storing electrical energy are not primary functions of a diode. Measuring devices like voltmeters are specifically designed for voltage measurement, while capacitors are used for storing electrical energy. While a diode can be part of a circuit that converts AC to DC, its primary role is to facilitate the unidirectional flow of current, making the option regarding its directional control the most accurate representation of its main function.