What is the primary purpose of a transformer in an electrical circuit?

The primary purpose of a transformer in an electrical circuit is to step up or step down voltage levels. Transformers are electrical devices that change the voltage of alternating current (AC) while maintaining the power level (minus losses). By adjusting the voltage, transformers are crucial for efficient power transmission over long distances. When voltage is stepped up, it reduces current, minimizing energy loss due to resistance in the wires. Conversely, stepping down voltage makes it safer for use in homes and businesses. This capability to modify voltage levels is essential for optimizing the distribution and consumption of electrical energy.

The other roles mentioned, such as storing electrical energy or measuring electrical current, are not functions of a transformer. Transformers do not generate energy; they simply modify the voltage of electrical signals passing through them.