What describes the operation of a transformer?

A transformer operates based on the principle of electromagnetic induction and is primarily used to increase or decrease voltage levels in alternating current (AC) systems while maintaining the overall power (minus losses) in the circuit. The ratio between the primary and secondary coil windings determines whether the voltage is stepped up or stepped down.

When the transformer is functioning, it transfers energy from the primary circuit to the secondary circuit by changing voltage levels, but the total input power (voltage multiplied by current) remains roughly equal to the output power (accounting for efficiency losses). This property is crucial for power distribution, as it allows electricity to be transmitted over long distances at high voltages, minimizing losses, and then transformed down to safer, usable levels for homes and businesses.

The other options do not accurately describe a transformer: it does not convert AC to DC, generate electricity, nor is it limited to power generation, as its main function is the transformation of voltage in power transmission systems.