What device is used to convert AC to DC?

The device used to convert alternating current (AC) to direct current (DC) is known as a rectifier. A rectifier allows the current to flow in only one direction, effectively transforming the AC wave, which oscillates between positive and negative voltages, into a steady DC output. This process is essential in applications where DC power is required, such as powering electronic devices and charging batteries.

Rectifiers can be of various types, including half-wave and full-wave rectifiers, depending on how they are designed to handle the AC waveform. The conversion process is crucial in many electronic systems where a stable DC voltage is necessary for optimal operation.

In contrast, the other options provided serve different functions in electrical and electronic systems. A transformer is primarily used to change the voltage level of an AC signal without converting it to DC. A capacitor stores and releases electrical energy but does not convert AC to DC. An inverter, on the other hand, performs the opposite function by converting DC back into AC, which is essential for powering AC devices from a DC source. Thus, the rectifier is the definitive answer to the question of which device performs the conversion from AC to DC.