What is the main function of a transformer in electrical systems?

The main function of a transformer in electrical systems is to change the voltage level in an electrical circuit. Transformers operate on the principle of electromagnetic induction to either step-up (increase) or step-down (decrease) voltage levels while maintaining the same frequency. This capability is crucial for efficient energy transmission over long distances. High voltage levels are used for transmission to minimize energy loss as heat, while lower voltage is applied in residential and commercial settings for safety and usability.

The other options highlight functions that are not associated with transformers. Increasing the frequency of current is not a role of transformers; instead, they operate at a constant frequency. Generating electricity from mechanical energy describes the operation of generators, not transformers. Similarly, storing electrical energy is a function of devices like batteries or capacitors, rather than a transformer. Thus, the ability of transformers to modulate voltage levels plays a key role in the overall efficiency and functionality of electrical distribution systems.