What is the primary purpose of an electrical transformer?

The primary purpose of an electrical transformer is to raise or lower AC voltages. Transformers operate on the principle of electromagnetic induction and are specifically designed to transfer electrical energy between two or more circuits through inductively coupled conductors. By adjusting the number of turns in the primary and secondary coils, transformers can effectively increase (step-up) or decrease (step-down) alternating current (AC) voltage levels. This capability is essential in power distribution systems, enabling electricity generated at power plants to be transmitted over long distances at high voltages, which reduces losses, and then transformed down to usable voltage levels for consumers.

The other choices do not accurately represent the primary function of a transformer; for instance, increasing DC voltage is not a function of transformers, as they do not operate with direct current. Similarly, converting AC to DC is a function of rectifiers, not transformers. Lastly, while transformers may have some minor energy storage characteristics, they are primarily not designed to store electrical energy. Thus, the choice that identifies raising or lowering AC voltages encapsulates the essential role that transformers play in the electrical system.