Strictly speaking, Eq. (26.16) implies that an infinite amount of time is required to discharge a capacitor completely. Yet for practical purposes, a capacitor may be considered to be fully discharged after a finite length of time. To be specific, consider a capacitor with capacitance C connected to a resistor R to be fully discharged if its charge q differs from zero by no more than the charge of one electron.
(a) Calculate the time required to reach this state if C = 0.920µF, R = 670kΩ, and Q0 = 7.00 µC. How many time constants is this?
(b) For a given Q0, is the time required to reach this state always the same number of time constants, independent of the values of C and R? Why or why not?