What is the significance of a transformer in relation to AC?

The significance of a transformer in relation to alternating current (AC) lies in its fundamental ability to facilitate the transformation of voltage levels, which is essential for the efficient transmission and distribution of electrical energy. Transformers operate on the principle of electromagnetic induction and can either step up (increase) or step down (decrease) AC voltage levels, enabling electricity to be transmitted over long distances with minimal energy loss.

By allowing for voltage adjustment, transformers make it feasible to transmit high voltage power efficiently from power plants to substations, and subsequently transform that high voltage to lower levels suitable for consumer use. This process helps mitigate energy losses when electricity is carried through power lines, thereby enhancing the overall efficiency of the electrical grid.

The other options do not accurately reflect the functional capabilities of transformers in relation to AC, as they either misunderstand or misrepresent how transformers interact with electrical systems. For instance, transformers do not change the frequency of AC; they maintain the same frequency while adjusting voltage levels. Additionally, it’s incorrect to state that they decrease efficiency or that they are not used with AC, as transformers are specifically designed for use with alternating current.