What electrical device transfers voltages from one circuit to another with a change in voltage?

A transformer is the electrical device designed specifically for transferring electrical energy between two or more circuits through electromagnetic induction, allowing for a change in voltage. It consists of two coils of wire, known as the primary and secondary coils, wound around a core. When an alternating current flows through the primary coil, it creates a changing magnetic field that induces a voltage in the secondary coil. The voltage change depends on the turns ratio of the coils: increasing the number of turns in the secondary coil compared to the primary coil steps up the voltage, while decreasing it steps down the voltage. This ability to adjust voltage levels is critical in power distribution systems.

Inductors, while related to magnetic fields and can store energy, do not provide voltage transformation between circuits. A dynamo generates direct current (DC) through mechanical means but is not used for voltage transformation. Rectifiers convert alternating current (AC) to direct current (DC) but do not change voltage levels between circuits. Thus, the transformer is unique in its capability to modify voltage between circuits while transferring electrical energy.