What role does a battery play in an electrical circuit?

A battery serves as a source of electrical energy in a circuit. Its primary function is to provide the necessary voltage to drive electric current through the circuit. When a battery is connected within an electrical circuit, chemical reactions occur inside it, converting stored chemical energy into electrical energy. This electrical energy is then available to power various components within the circuit, such as resistors, lights, motors, and more.

The other options describe functions that do not apply specifically to batteries. For instance, while batteries do store energy, their main defining role in a circuit is to supply electrical power rather than merely storing it. The conversion of mechanical energy into electrical energy is typically the function of devices like generators rather than batteries. Lastly, regulating the flow of current is a task assigned to other components, such as resistors and transistors, rather than the battery itself, which predominantly acts to supply power.