Which device is used to change voltage levels in an alternating current circuit?

Which device is used to change voltage levels in an alternating current circuit?

• A. Transformer
• B. Generator
• C. Solenoid
• D. Electric Motor

Answer: (A)

Transformers change voltage levels in alternating current circuits by using mutual induction between two coils wrapped around a magnetic core. When AC flows in the primary winding, it creates a changing magnetic flux that links to the secondary winding, inducing a voltage there. The output voltage scales with the turns ratio of the windings, so you can step the voltage up or down as needed. This only works with AC because the changing flux is essential to induce the secondary voltage; applying DC would cause only a brief transient and then no sustained output because the flux would settle and stop changing. This is different from a generator, which creates electrical energy from mechanical work rather than adjusting an existing voltage in a circuit. A solenoid is simply a coil that can generate a magnetic field, not a device designed to set voltage levels. An electric motor converts electrical energy into mechanical energy, not to modify voltage in a circuit.

Transformers change voltage levels in alternating current circuits by using mutual induction between two coils wrapped around a magnetic core. When AC flows in the primary winding, it creates a changing magnetic flux that links to the secondary winding, inducing a voltage there. The output voltage scales with the turns ratio of the windings, so you can step the voltage up or down as needed. This only works with AC because the changing flux is essential to induce the secondary voltage; applying DC would cause only a brief transient and then no sustained output because the flux would settle and stop changing.

This is different from a generator, which creates electrical energy from mechanical work rather than adjusting an existing voltage in a circuit. A solenoid is simply a coil that can generate a magnetic field, not a device designed to set voltage levels. An electric motor converts electrical energy into mechanical energy, not to modify voltage in a circuit.