Which phenomenon allows energy transfer between transformer windings without direct electrical contact?

Which phenomenon allows energy transfer between transformer windings without direct electrical contact?

• A. Magnetic induction
• B. Electrostatic coupling
• C. Direct conduction
• D. Thermal transfer

Answer: (A)

The energy transfer happens through changing magnetic flux linking the windings, which is magnetic induction. When current in the primary coil changes, it creates a time-varying magnetic field in the core. This changing flux threads the secondary winding, and by Faraday’s law a voltage is induced in that winding. With a load connected, current flows in the secondary, drawing power from the magnetic field. Since the windings aren’t connected by a wire, energy moves via the magnetic field itself rather than direct contact. The other ideas don’t fit: electrostatic coupling would rely on static electric fields, direct conduction would require a physical connection, and thermal transfer is about heat, not electrical energy transfer.

The energy transfer happens through changing magnetic flux linking the windings, which is magnetic induction. When current in the primary coil changes, it creates a time-varying magnetic field in the core. This changing flux threads the secondary winding, and by Faraday’s law a voltage is induced in that winding. With a load connected, current flows in the secondary, drawing power from the magnetic field. Since the windings aren’t connected by a wire, energy moves via the magnetic field itself rather than direct contact. The other ideas don’t fit: electrostatic coupling would rely on static electric fields, direct conduction would require a physical connection, and thermal transfer is about heat, not electrical energy transfer.