What is the main function of a transformer in an electrical system?

The primary role of a transformer in an electrical system is to change the voltage of electrical power. Transformers operate on the principle of electromagnetic induction, enabling them to step voltage levels up or down to meet the requirements of various electrical applications.

In practical terms, a transformer can increase (step-up) voltage to minimize energy losses over long distances during transmission, or decrease (step-down) voltage for safe distribution to homes and businesses. By doing this, transformers help maintain an efficient and stable electrical system, ensuring that power is delivered at the appropriate voltage levels as required by different devices and systems.

The other options do not accurately represent the core function of a transformer. For instance, increasing current is not a function of a transformer; rather, it alters voltage. Measuring electrical resistance is the role of an ohmmeter or similar instrument, and providing backup power usually involves different components like generators or battery systems rather than transformers.