What device is used to change direct current into alternating current?

The conversion of direct current (DC) to alternating current (AC) is primarily accomplished using a device known as a converter. This device is specifically designed to change the voltage and current characteristics of electrical energy from one form to another. In the context of electrical systems, a converter refers to equipment that can change the characteristics of electrical signals, allowing DC to be transformed into AC.

A transformer, in contrast, is used to increase or decrease voltage in alternating current systems but does not convert DC into AC. A rectifier performs the opposite function, converting AC into DC, while a resistor is a passive component that limits the flow of current in a circuit but does not change the nature of the current between AC and DC.

Understanding these distinctions is crucial in comprehending how electrical systems operate and the roles of various components within them.