What device is used to change voltage levels in AC circuits?

The transformer is specifically designed for changing voltage levels in alternating current (AC) circuits. This device operates on the principle of electromagnetic induction, which allows it to increase (step-up) or decrease (step-down) voltage levels without changing the frequency of the electrical power.

When an AC voltage is applied to the primary coil of the transformer, it creates a magnetic field that induces a voltage in the secondary coil. The ratio of turns between the primary and secondary coils determines whether the voltage will be increased or decreased. For example, if the secondary coil has more turns than the primary coil, the voltage will be stepped up, whereas if it has fewer turns, the voltage will be stepped down.

In summary, the transformer is crucial for efficiently managing voltage levels in AC systems, making it an essential piece of equipment in electrical engineering and various applications including power distribution and electrical devices.