What role do electromagnetic induction and the turns ratio play in transformer function?

Electromagnetic induction and the turns ratio are fundamental to how transformers function. The correct answer highlights that these two aspects specifically determine the voltage change that occurs based on the arrangement of the coils.

In a transformer, alternating current flowing through the primary coil generates a changing magnetic field, which induces a voltage in the secondary coil through electromagnetic induction. The amount of induced voltage in the secondary coil is directly related to the turns ratio, which is the ratio of the number of turns of wire in the primary coil to the number of turns in the secondary coil. This relationship allows for the stepping up or stepping down of voltage. For instance, if the secondary coil has more turns than the primary, the voltage in the secondary will be higher, and conversely, if the secondary has fewer turns, the voltage will be lower.

Thus, the interplay between electromagnetic induction and the turns ratio is essential for controlling and transforming voltage levels in electrical circuits, which underpins the operational principles of transformers.