What is the purpose of a transformer in an electrical circuit?

The purpose of a transformer in an electrical circuit is specifically to change the voltage level of alternating current (AC) electricity. Transformers operate on the principle of electromagnetic induction, allowing them to step up (increase) or step down (decrease) voltage levels while ideally maintaining the same power level across the primary and secondary coils, minus some losses.

In AC systems, voltage levels need to be adjusted for efficient power transmission and distribution. For instance, stepping up the voltage can minimize energy loss over long distances by reducing current, which decreases resistive losses in the conductors. Similarly, stepping down the voltage is necessary for safe distribution to residential and commercial properties.

Transformers cannot work with direct current (DC) because DC does not create a changing magnetic field, which is required for the operation of a transformer. Similarly, transformers do not convert electrical energy into thermal energy as their primary function; rather, they transfer electrical energy with varying voltage levels. Amplification of electrical signals is a different process that typically involves other devices, such as amplifiers, rather than transformers.