Electrical Engineering - Capacitors - Discussion

If a resistor is connected in series with the capacitor forming an RC circuit, the capacitor will charge up gradually through the resistor until the voltage across the capacitor reaches that of the supply voltage. The time called the transient response, required for this to occur is equivalent to about 5 time constants or 5T. This transient response time T, is measured in terms of T = R x C, in seconds, where R is the value of the resistor in ohms and C is the value of the capacitor in Farads. This then forms the basis of an RC charging circuit were 5T can also be thought of as "5 x RC".

Time Constant (t) : A measure of time required for certain changes in voltages and currents in RC and RL circuits. Generally, when the elapsed time exceeds five time constants (5t) after switching has occurred, the currents and voltages have reached their final value, which is also called steady-state response.

V (Capacitor) = V(1-e^[-t/T]).

Put [t=T].

V(c) = V(1-e^[-1]).

As we know e^[-1] = 0.37 above answer will be 0.63.

Similarly put [t = 5T].

V(c) = V(1-e^[-5T/T]).

V(c) = V(1-e^[-5]).

V(c) = V(0. 9932) which is nearly equal to 100% it means at 5T we are getting the capacitor fully charged.

In @Priyanka's explanation she wrote current it must be replace by voltage.

Like 1 Ts 63.2% of max voltage.

Mathematical constant e, specifically 1-e^{-1}, more specifically as voltage to charge the capacitor versus time.

Charging V(t) = V0 (1-e^{-t/tau}).

Tau = RC.

Time constant and current relationship is :

1Ts 63.2% of max current.

2Ts 86.5% of max current.

3Ts 95% of max current.

4Ts 98.2% of max current.

5Ts 100% of max current.

@Thamin.

You'r explained but very confuse. Any way you are only person is tried to answer this question. Thank you.

(please explain me again once to short answer).

Hi, @Birendra Das.

How about it is in 6RC, 99.75 percent is much closer to 100 rather than 99.32 percent?

@Thamin.

You are answer is right but, little confusion. Please explain how you gate 5T?

Why is it 5T constant only ?

I mean how did you figure that out ?

I don't understand the question clearly. Can anyone explain me?