What condition must be met for maintaining a capacitor's functionality in electrical circuits?

To ensure a capacitor functions correctly in electrical circuits, it is essential for it to operate within a specific percentage of its rated capacitance. This requirement is vital because a capacitor designed for a particular capacitance value has certain expected characteristics and behaviors for that rating. If the capacitance deviates too much from the specified range, it can cause the circuit to malfunction, leading to issues such as phase angle shifts in AC applications, reduced filtering capability in power supply circuits, and overall imperfect performance in applications that rely on precise timing.

Operating a capacitor within a specific tolerance ensures it can effectively store and release energy as required by the circuit’s design. For example, common tolerance levels for capacitors might range from ±5% to ±20%, depending on the type and application of the capacitor. Within this range, the capacitor can successfully meet the operational demands of the circuit.

The other options imply unrealistic conditions or disregard the importance of capacitance entirely, which does not align with the fundamental principles of how capacitors work in electrical circuits.