Electrical Engineering - Inductors - Discussion

Discussion :: Inductors - General Questions (Q.No.19)

19.

A 320 H coil is in series with a 3.3 k resistor. How long does it take for current to build up to its full value?

 [A]. 0.48 s [B]. 0.48 ms [C]. 0.48 s [D]. 48 s

Explanation:

No answer description available for this question.

 Kirthikumar Rao said: (Nov 23, 2011) time constant T=(L/R) to reach max current it will take appr 5T time=5(320u/3.3k) =0.48us

 Feliciano said: (Apr 25, 2012) Time constant for an RL circuit is not R*L! It is instead L/R, which makes Time Constant equal to 5* (320u/3. 3K) = 0.4848.

 Rrgiri said: (Mar 1, 2014) How it s possible ? @Vikas time constant is R/L or R*L ?

 Rajat said: (Mar 4, 2014) What is time constant?

 Ganesh said: (Apr 26, 2014) Time constant for RL circuit is L/R SO time constant = (320*10^(-6)/3.3*10^(3)) time taken to reach final value is approximately 5T = 0.48*10^(-6).

 Ekanath Methre said: (Apr 30, 2015) How did you took 5T? Please explain it.

 Tejas Gouda said: (May 6, 2015) Why we need to multiply it by 5? How the time taken will be approximately 5T? Why can't it be 10T? Time constant means L/R not LR.

 11Kv said: (Jun 12, 2015) Time constant for inductor is L/R.

 Roopesh D M said: (Jun 18, 2015) The time required for the current flowing in the LR series circuit to reach its maximum steady state value is equivalent to about 5 time constants or 5T. This time constant T, is measured by T = L/R, in seconds, were are is the value of the resistor in ohms and L is the value of the inductor in Henries.

 Stuti Kushwaha said: (Feb 15, 2016) Time constant of LR circuit is L/R. So here after multiplying by 5 we get answer is 0.484 micros.

 Shoaib said: (Oct 28, 2016) TIME CONSTANT AND CURRENT RELATIONSHIP: 0 0% 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. So, first we know that the maximum possible current through the circuit will be full, means the 100% of max current and the time constant will be 5Ts so, Time constant => T= (L/R) = (320u/3.3k). When it reaches max current(100%) it will take 5Ts. So 5Ts = 5(320u/3.3k), =0.48us.

 Dhaval said: (May 4, 2017) Thanks @Shoaib.

 Rehman said: (Dec 5, 2019) Good @Shoaib.