ATT Field Competency (FC) Practice Test 2026 - Free Field Competency Practice Questions and Study Guide

Transformers operate primarily on the principle of mutual inductance. This principle involves two coils of wire, called the primary and secondary windings, that are placed in proximity to each other. When an alternating current flows through the primary winding, it creates a varying magnetic field around it. This changing magnetic field induces a voltage in the secondary winding through the process of mutual inductance.

Mutual inductance is the key factor in how transformers transfer electrical energy from one coil to another without direct electrical connection. It allows for the stepping up or stepping down of voltage levels, depending on the ratio of turns between the primary and secondary windings. This ability to change voltage levels is crucial in power distribution and many electrical applications, making mutual inductance a fundamental principle in the operation of transformers.