What is the primary function of a rectifier in a power supply?

The primary function of a rectifier in a power supply is to convert alternating current (AC) to direct current (DC) voltage. AC voltage alternates in polarity and is typically the form of electricity supplied by power companies, while many electronic devices require DC voltage to operate effectively. A rectifier achieves this conversion by allowing current to flow in only one direction, effectively blocking the reverse polarity of the AC voltage. This process results in a smooth, unidirectional flow of current, often referred to as pulsating DC, which can then be further filtered and regulated for use in electronic devices.

The other choices describe functions that are not the primary role of a rectifier. Increasing AC voltage levels typically involves a transformer, not a rectifier. Storing electrical energy is the function of capacitors or batteries, and regulating current flow is the responsibility of voltage regulators and similar components, which maintain a stable output even when input conditions fluctuate.