What does an AC power source utilize to supply the correct voltage?

An AC power source typically utilizes a transformer to supply the correct voltage. A transformer operates on the principle of electromagnetic induction and is designed to either step up or step down the voltage levels of alternating current (AC). It consists of two coils of wire, known as the primary and secondary coils, wrapped around a magnetic core. When an alternating current flows through the primary coil, it generates a varying magnetic field, which induces a voltage in the secondary coil. This allows the transformer to adjust the voltage level to meet the requirements of various electrical devices or systems.

In contrast, other options serve different functions or do not apply to the provision of voltage in an AC system. A bridge rectifier, for example, converts AC to DC and is not used to supply AC voltage. A DC generator produces direct current and would not be relevant in the context of an AC power supply. Meanwhile, a smoothing capacitor is used in power supply circuits to smooth out fluctuations in voltage after rectification but does not generate or supply the AC voltage on its own. Therefore, the transformer is the key device that ensures the correct voltage supply in an AC system.