Final answer:
A transformer is a device that transforms voltages from one value to another. It converts alternating current to a different voltage.
Step-by-step explanation:
A transformer is a device that transforms voltages from one value to another. It is used to convert alternating current (AC) to a different voltage. For example, many electrical devices such as cell phones, laptops, and power tools have a transformer built into their plug-in unit that changes the high voltage AC from the power outlet to a lower voltage that the device can use.