What does a step-down transformer do?

A step-down transformer is designed to reduce the voltage from a higher level to a lower level while increasing the current flow. When alternating current passes through a transformer, the principle of electromagnetic induction allows it to adjust the voltage and current based on the turns ratio of the wire coils in the transformer. In a step-down transformer, the primary coil has more turns than the secondary coil, which results in a decrease in voltage when energy is transferred to the secondary coil.

As the voltage decreases, there is a corresponding increase in current, because power (which remains constant, ignoring losses) can be expressed as the product of voltage and current (P = V x I). Therefore, when the voltage is reduced, the current must increase to keep power balanced. This is a fundamental concept of transformers, making the correct answer a description of their operational principle in electrical engineering.