Question

How fast can a capacitor charge?

Answer 1

1. The time constant is a concept that is important to understand when talking about how capacitors charge and discharge. A capacitor's time constant is calculated as the product of its resistance and capacitance.
2. The formula is $\tau =RC$ to get a capacitor's time constant. This number provides the amount of time (in seconds) needed for a capacitor to charge to $63\%$ of the current-voltage. The capacitor will be charged to more than $99\%$ of the provided voltage after five-time constants.
3. The capacitor needs infinity of time to charge completely
4. Thus, the following formula can be used to determine how long it takes a capacitor to charge:

Time for a capacitor to charge$=5RC$

Hence, it takes five times as long to charge the capacitor to $99\%$ capacity.