Transformers are used in AC systems to alter voltage levels. What is their main operational principle?

The main operational principle of transformers in AC systems is induction. Transformers utilize electromagnetic induction to transfer electrical energy between two or more coils. The primary coil receives alternating current, which creates a varying magnetic field. This magnetic field induces a voltage in the secondary coil according to Faraday's law of electromagnetic induction.

This principle enables transformers to effectively step up or step down voltage levels without changing the frequency of the electrical system. By adjusting the number of turns in the primary and secondary coils, transformers can either increase or decrease the voltage, making them essential for efficient energy transmission over long distances.

Capacitance, conductivity, and resistance are not the foundational principles of transformer operation. While they play roles in different aspects of electrical systems, they do not relate directly to the fundamental mechanism by which transformers operate to change voltage levels.