Electrical Engineering - Capacitors - Discussion
Discussion Forum : Capacitors - General Questions (Q.No. 11)
11.
A 4.7 M
resistor is in series with a 0.015 
F capacitor. The combination is across a 12 V source. How long does it take the capacitor to fully charge?
resistor is in series with a 0.015 F capacitor. The combination is across a 12 V source. How long does it take the capacitor to fully charge?Discussion:
20 comments Page 1 of 2.
Yashwanth said:
5 years ago
Time Constant of Capacitor = 5RC.
T = 5 * (4.7*10^-6)(0.015*10^-3).
T = 352.
T = 5 * (4.7*10^-6)(0.015*10^-3).
T = 352.
Nitin Dhotre said:
6 years ago
Q = RC*60/V.
(1)
Dhiraj said:
7 years ago
It is fully charged so multiply by 5.
Lalithanandigam said:
8 years ago
As we know v =v(1-epower(-t/rc)).
So let us take t=Rc then v=v*0.63.
If u take t=5rc then v=v*0.993..
So during t=5rc capacitor is fully charged..
If you want to find the voltage across the capacitor after time t =5rc then we can use v=12*5*r*c.
So let us take t=Rc then v=v*0.63.
If u take t=5rc then v=v*0.993..
So during t=5rc capacitor is fully charged..
If you want to find the voltage across the capacitor after time t =5rc then we can use v=12*5*r*c.
Manisha said:
8 years ago
What is the role of voltage here?
Saurabh Kr. Verma said:
8 years ago
If t=5rc then it means there is no effect of 12V on it?
Is it take same time across any voltage?
Please tell me that.
Is it take same time across any voltage?
Please tell me that.
Abhishek said:
8 years ago
@Murtadha
The time required to charge a capacitor to 100% is 5T. Where t=R*c. that u got. not multiply that T with 5 you will get the answer.
The time required to charge a capacitor to 100% is 5T. Where t=R*c. that u got. not multiply that T with 5 you will get the answer.
Murtadha said:
9 years ago
Q = C*V = 0.015*10^-6 *12 =1.8^-7 colmb.
I = V/R = ( 12 / 4.7*10^6) =2.55*10^-6 amper.
I = Q/t 2.55*10^-6 = 1.8*10^-6 /t.
t= 70.5 ms.
So I think the choice (D) correct not (b).
I = V/R = ( 12 / 4.7*10^6) =2.55*10^-6 amper.
I = Q/t 2.55*10^-6 = 1.8*10^-6 /t.
t= 70.5 ms.
So I think the choice (D) correct not (b).
Apoorva said:
9 years ago
Please give full reason?
Kanwaljit singh said:
9 years ago
5RC, in formula 5 is include because capacitor takes 5 times more time to charge itself when it is in series with resistor than normal charging so that why we use 5 constant in the formula.
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