Consists of two coils linked by an iron core; used to step up and step down AC voltages; energy transferred magnetically with no electrical connection between coils.

• A. Transformer
• B. Inductor
• C. Generator
• D. Motor

Answer: (A)

This is about transferring energy between circuits using magnetic coupling in a device with two coils on a common iron core. When alternating current flows in the primary winding, it creates a changing magnetic flux in the core that links to the secondary winding. That changing flux induces a voltage in the secondary coil according to Faraday’s law. The voltage ratio between the windings depends on their turns; more turns on the secondary produce a higher voltage (step-up), fewer turns produce a lower voltage (step-down). The iron core provides a low-reluctance path, concentrating the magnetic field and making the energy transfer efficient at AC frequencies. This setup relies on energy moving through the magnetic field rather than through a direct electrical connection, which is why it can both raise and lower voltage without wires linking the two sides. It differs from an inductor, which is typically a single coil used for storing energy or shaping current and usually does not transfer energy to another circuit. It also differs from a generator, which converts mechanical energy to electrical energy, and from a motor, which converts electrical energy to mechanical energy.