PSI Journeyman Practice Exam 2025 – The All-in-One Guide to Success!

A transformer primarily functions to change the voltage levels in an electrical circuit. It achieves this by using electromagnetic induction to transfer energy between its coils (the primary and secondary) at different voltages. When alternating current (AC) flows through the primary coil, it generates a magnetic field that induces a current in the secondary coil. Depending on the turns ratio between the primary and secondary coils, the transformer can either step up (increase) the voltage or step down (decrease) the voltage.

This capability is crucial in electrical power distribution, where high voltage is used for efficient transmission over long distances to minimize energy loss. Once the electricity reaches its destination, transformers lower the voltage to safe and usable levels for consumers and businesses. Therefore, the correct function of a transformer in an electrical circuit is indeed to change the voltage levels.