CAMRT Radiography Practice Exam 2026 - Free Radiography Practice Questions and Study Guide

Transformers require alternating current (AC) for their operation due to the principle of electromagnetic induction. When alternating current flows through the primary coil of the transformer, it creates a varying magnetic field. This varying magnetic field then induces a voltage in the secondary coil according to Faraday's law of electromagnetic induction.

Using direct current (DC) would not be effective for transformers. DC provides a constant voltage that does not change over time, which means it does not create a changing magnetic field necessary for induction in the secondary coil. As a result, transformers would not function as intended with DC input.

The option suggesting both AC and direct current is also incorrect because transformers are specifically designed to operate with AC. They rely on the alternating nature of the current to transfer electrical energy efficiently from one coil to another. Therefore, transformers exclusively require AC current for their operation.