What is an electric device that uses electromagnetism to change voltage from one level to another?

The device that uses electromagnetism to change voltage from one level to another is a transformer. Transformers operate based on the principle of electromagnetic induction, which involves the transfer of electrical energy between two or more coils of wire (the primary and secondary windings) through a magnetic field. When an alternating current flows through the primary winding, it generates a magnetic field that induces a voltage in the secondary winding. The ratio of turns between the primary and secondary coils determines whether the transformer increases (step-up transformer) or decreases (step-down transformer) the voltage.

This fundamental ability to adjust voltage levels makes transformers essential in electrical power distribution, allowing for efficient transmission of electricity over long distances by stepping up the voltage for transmission and stepping it down for safe use. Other devices like capacitors, inductors, and rectifiers serve different functions in electrical circuits, but they do not specifically change voltage levels through the same electromagnetic principle utilized by transformers.