The correct answer is: The time constant of an R-C circuit is defined as the time during which capacitor charging voltage actually rises to 63.2% of its final value.
The time constant of an R-C circuit is the time it takes for the capacitor to charge to 63.2% of its final value, or to discharge to 36.8% of its initial value. It is denoted by the Greek letter tau (Ï) and is equal to the product of the resistance (R) and the capacitance (C).
The time constant can be used to calculate the voltage across the capacitor at any time after the switch is closed. The voltage across the capacitor is given by the equation:
V(t) = Vf(1 – e^(-t/Ï))
where Vf is the final voltage across the capacitor, t is the time, and Ï is the time constant.
The time constant can also be used to calculate the time it takes for the capacitor to charge to a certain percentage of its final value. For example, the time it takes for the capacitor to charge to 63.2% of its final value is equal to Ï.
The time constant is a useful parameter for analyzing the behavior of R-C circuits. It can be used to calculate the voltage across the capacitor at any time, or the time it takes for the capacitor to charge to a certain percentage of its final value.