Which of the following best describes what a step-down transformer converts?

• A. $\mathrm{High\; voltage},\mathrm{low\; current}\mathrm{AC}\to \mathrm{low\; voltage},\mathrm{high\; current}\mathrm{AC}$
• B. $\mathrm{Alternating\; current}\to \mathrm{direct\; current}$
• C. $\mathrm{Low\; voltage},\mathrm{high\; current}\mathrm{AC}\to \mathrm{high\; voltage},\mathrm{low\; current}\mathrm{AC}$
• D. $\mathrm{Direct\; current}\to \mathrm{alternating\; current}$

Answer: (A)

Verified step by step guidance

1. Understand that a transformer is a device used to change the voltage and current levels of alternating current (AC) electricity without changing its frequency.
2. Recall that a step-down transformer specifically reduces the voltage from a higher value to a lower value while increasing the current proportionally, because power (ignoring losses) is conserved.
3. Recognize that the input to a transformer is always alternating current (AC), so it does not convert AC to direct current (DC) or vice versa.
4. Identify that the primary coil of the transformer has more turns than the secondary coil in a step-down transformer, which causes the voltage to decrease and the current to increase on the secondary side.
5. Conclude that the best description of a step-down transformer is that it converts high voltage, low current AC into low voltage, high current AC.