The basic operational principle of transformers is the __________ between primary and secondary windings.

• A. Interconnection
• B. Size difference
• C. Mutual Induction
• D. Electron transfer

Answer: (C)

Mutual induction is the basic idea because a transformer transfers energy through magnetic coupling between its windings. When alternating current flows in the primary, it creates a changing magnetic flux in the core that links the secondary winding. This changing flux induces a voltage in the secondary according to Faraday’s law, with the voltage ratio set by the turns ratio. The windings remain electrically isolated; energy moves through the magnetic field rather than by direct electron transfer between coils. Interconnection would imply a physical electrical connection, which isn’t how transformers work; size differences affect voltage and current capacity but not the fundamental mechanism; electron transfer between windings doesn’t occur.