Ham Amateur Radio Technician Practice Exam 2026 - Free Technician Practice Questions and Study Guide

The presence of voltage across the secondary winding of a transformer when an AC voltage source is applied to its primary winding is a direct result of mutual inductance. In a transformer, the primary winding is energized by the alternating current, which creates a varying magnetic field in the core of the transformer. This changing magnetic field induces an electromotive force (EMF) in the secondary winding through the process known as electromagnetic induction.

Mutual inductance is the phenomenon where a change in current flowing through one coil (the primary winding) induces a voltage in another coil (the secondary winding) that is magnetically linked to it. The effectiveness of this induction depends on several factors, including the number of turns in each winding, the core material, and the frequency of the alternating current. The induced voltage in the secondary winding is directly proportional to the change in current in the primary winding, exemplifying Faraday's law of electromagnetic induction.

Other factors like electrical resistance and capacitance do not contribute to the induction process in a transformer. While there may be some voltage drops due to resistance within the circuit, it is not the principle mechanism causing voltage in the secondary winding. Thus, mutual inductance is the key factor that results in the appearance of voltage across the transformer's