What kind of energy transformation does a power supply unit (PSU) perform?

A power supply unit (PSU) is designed primarily to convert alternating current (AC) from the electrical grid into direct current (DC) that can be used by electronic devices and components. This transformation is crucial because most electronic devices, such as computers, require DC for their operation, while the input from the electrical outlets is typically AC.

The PSU not only converts the voltage level but also filters and regulates the power to ensure consistent and stable output for electronic components. The process involved includes rectification, where AC is converted to DC, followed by regulation to maintain the desired voltage level despite fluctuations in the input voltage or load conditions.

In summary, the correct answer accurately reflects the primary function of a power supply unit. Its main purpose is to facilitate the transformation from AC to DC, aligning with the operational needs of various electronic devices.