The charge stored within a capacitor is determined by the product of the capacitance and voltage across the capacitor, meaning that exactly how long it takes to reduce the charge of the capacitor to 10 μc will depend on the original capacitance and voltage of the capacitor. To reduce the capacitor's charge to 10 μc, an opposing voltage or current must be introduced to the capacitor in order to reduce the voltage across the capacitor/discharge the capacitor. Generally, as the capacitance increases, the time it takes to discharge the capacitor increases. As such, the most accurate answer can be found by first determining the original capacitance and voltage of the capacitor and then utilizing one of the standard capacitor discharge equations to calculate the time it would take.
