What does a transformer do in a circuit?

A transformer is a device that increases or decreases voltage in an alternating current (AC) circuit. It operates on the principle of electromagnetic induction, where an alternating current in one coil (the primary coil) generates a magnetic field that induces a voltage in a second coil (the secondary coil). The ratio of turns of wire in the primary and secondary coils determines whether the voltage is increased or decreased.

For example, if the secondary coil has more turns than the primary coil, the transformer will increase the voltage (step-up transformer). Conversely, if the secondary coil has fewer turns, it will decrease the voltage (step-down transformer). This ability to change voltage levels is crucial in power distribution systems, allowing electricity to be transmitted over long distances efficiently and then transformed to usable levels for homes and businesses.

Other functions mentioned, such as converting DC to AC or storing electrical energy, do not align with the primary role of a transformer. While a switch can control flow within a circuit, it does not perform the voltage transformation that is central to a transformer's purpose.