Doubts on inductance....

1) In a series resonant LCR circuit the voltage across R is 100V and R= 1KΩ, C=2μF. The resonant frequency ω is 200 rad s-1. At resonance, the voltage across L is:

a)40 b)250V c)4*10-3V d)2.5*10-2V

2)A coil of inductance 300mH and resistance 2Ω is connected to a source of voltage 2v. The current reaches half of its steady state value in:

a)0.3s b)0.15s c)0.1s d)0.05s

4 Answers

1
venkateshan ·

(2)
you know that,

i = i0(1-e-Rt/L)

Now, the current reaches half of the steady state value....
therefore, put i = i0/2

1/2 = (1 - e-2t/0.3)

2t/0.3 = ln 2

2t = 0.09
t = 0.045 s which is approx. 0.05 s

1
venkateshan ·

sorry..adarsh
I haven't studied the chapt AC properly... so i cud nt ans ur 1 st q.

1
adarsha ·

thanx 4 d solution.....neone with q no 1 ?????

49
Subhomoy Bakshi ·

ωL=1ωC

the net resistance will be only due to resistance R

i= VR

V across inductance = i.Xc = i(ωL)=VωRC

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