# Electrical Engineering - Capacitors - Discussion

Discussion Forum : Capacitors - General Questions (Q.No. 4)

4.

In Question 6, the capacitor will reach full charge in a time equal to approximately

Discussion:

15 comments Page 1 of 2.
Sindu said:
7 years ago

@Priyanka you have explained clearly.

Saurav said:
7 years ago

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

Mak said:
7 years ago

Hi, @Birendra Das.

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

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

Birendra Das said:
8 years ago

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.

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.

Yagnesh said:
8 years ago

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.

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.

Priyanka said:
8 years ago

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.

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.

Tejas said:
8 years ago

To reach 100% full charge we need to consider 5T.

Arnav said:
8 years ago

Please explain in shortcut.

(1)

Rehan said:
9 years ago

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.

Vimal said:
9 years ago

Why is it 5T constant only ?

I mean how did you figure that out ?

I mean how did you figure that out ?

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