Which of the following would best describe a transformer?

A transformer is a critical component in electrical systems, primarily designed to transfer electrical energy between two or more circuits through electromagnetic induction. It functions by changing voltage levels while maintaining the power balance (ignoring losses).

The relationship between voltage and current in a transformer is governed by the principle of conservation of energy: when the voltage is stepped up, the current is stepped down, and vice versa. This means that while it changes voltage levels, it automatically alters current levels in accordance with the power equation (Power = Voltage x Current).

The ability of a transformer to alter both voltage and current levels is a fundamental characteristic of how it operates within power distribution systems, enabling efficient transmission of electricity over long distances. Thus, the description of a transformer as a device that changes both voltage and current levels accurately encapsulates its primary function.