What is the definition of a transformer?

• A. A device that stores energy magnetically
• B. A transformer is a component of 2 or more coils coupled by magnetic induction
• C. A device that converts DC to AC
• D. A resistor to limit current

Answer: (B)

Transformers transfer electrical energy from one circuit to another using two or more coils that are magnetically linked. When current in the primary coil changes, it creates a changing magnetic flux in the core, which induces voltage in the secondary coil through mutual induction. The voltage and current on each side are related by the turns ratio, so the device can step voltage up or down as needed. This energy transfer relies on alternating or changing currents, since a steady DC would produce a constant magnetic field and no continuous induction. A transformer isn’t a energy storage device like a battery, nor is it a resistor or a DC-to-AC converter.