Which device allows the transfer of electric energy between two insulated circuits using magnetic induction?

The transfer of electric energy between two insulated circuits using magnetic induction is accomplished by a transformer. This device operates on the principle of electromagnetic induction, where an alternating current in one coil produces a magnetic field that induces a current in another coil. The transformer typically consists of two or more coils wrapped around a core, which enhances the magnetic coupling between the coils.

Transformers are fundamental in electrical systems for voltage transformation, allowing for efficient transmission of electricity over long distances by stepping up or stepping down voltages as required by the application. This functionality is crucial in power distribution networks, enabling the safe and effective delivery of electrical energy.

Other options are designed for different purposes. Capacitors store electrical energy in an electric field, relays are used for switching and controlling circuits, and inductors are components that store energy in a magnetic field when electrical current flows through them. While these devices are important in electrical systems, they do not serve the specific function of transferring energy through magnetic induction between insulated circuits in the way that transformers do.