What determines the limits of the voltage in a circuit?

The limits of the voltage in a circuit are primarily determined by the battery. A battery provides a fixed voltage output that sets the maximum potential difference across components connected in the circuit. The voltage supplied by the battery dictates how much electrical energy is available to be converted into other forms of energy, such as light, heat, or motion, when current flows through the circuit.

While capacitors can influence voltage in a circuit—by storing charge and affecting the voltage across other components during charging and discharging—they do not set the inherent limit of the circuit's voltage. Resistors, on the other hand, modify the current flow based on voltage but are also not responsible for setting the maximum voltage limit. Therefore, the battery is the primary determinant of voltage levels in electrical circuits.