What is the primary function of a transformer in electrical circuits?

The primary function of a transformer is to convert voltage levels from one value to another. Transformers operate on the principle of electromagnetic induction, allowing them to increase (step-up transformer) or decrease (step-down transformer) the voltage of alternating current (AC) while maintaining the same frequency. This capability is crucial for transmitting electrical power efficiently over long distances, where high voltage reduces current and thus minimizes energy loss as heat due to resistance in the wires.

Transformers do not store electrical energy; instead, they transfer energy between circuits through electromagnetic fields. They also do not play a role in detecting electrical faults within a circuit, as that function is typically handled by circuit protection devices or monitoring systems. Additionally, while transformers can influence signal levels in specific applications, they do not amplify electrical signals in the way that an amplifier would, which is designed primarily to increase the amplitude of signals. Consequently, the correct answer accurately captures the distinct and essential role transformers play in electrical systems.