What is a transformer used for?

A transformer is fundamentally designed to change the voltage levels in an electrical system. This function is crucial in electrical power distribution, where efficient transmission of electricity over long distances is necessary. When electricity is transmitted at high voltages, it minimizes energy loss due to resistance in the wires. Transformers can either step up voltage (increase) for transmission efficiency or step down voltage (decrease) for safe utilization in homes and businesses.

While the other functions mentioned are important in electrical systems, they are not the primary use of a transformer. Increasing electric current is not something a transformer does; in fact, according to the principles of electric power, when voltage is increased, the current is decreased, assuming power is constant. Measuring electric resistance is the job of a multimeter or ohmmeter, rather than a transformer. Lastly, converting AC to DC is a function of rectifiers, not transformers, which are designed specifically for handling alternating current without facilitating direct current conversion.