LRC circuits

  • Thread starter popo902
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  • #1
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Homework Statement


An AC generator in an LRC circuit produces a voltage V(t) = 1.414sin(wt) = 1.414sin(1000t)
The values of inductance, capacitance, and resistance are shown in the diagram. Recall the w = 2pi*f.

i made a picture of the diagram:
http://i36.photobucket.com/albums/e47/jo860/lrc.jpg


a) What is the rms voltage supplied by the generator?

b) What is the maximum current in the circuit?

c)What is the phase difference between the AC generator and the current flowing in the current?

(I made w = omega)


Homework Equations



Vrms = Vpeak/ sqrt(2)


The Attempt at a Solution


im doing practice final and i don't have the answers
i just want to run them by some people just in case i got the thinking wrong
so for,

a) Since V(t) = Vpeak *sin(wt), Vpeak = 1.414, so then Vrms = 1.414/sqrt(2) =~ 1V, right?

b) This is one i'm mostly confused on. I'm not sure how to go about this, but i'm leaning toward the power equation except there is no power value here. This is assuming ipeak is what it's asking for....so...:(


c) I remember that RLC circuits are usually conductive, so the phase would be around 90, with the current leading, right?

and that's what i have so far
 
Last edited:

Answers and Replies

  • #2
245
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for (a) your answer is right.
for (b) you need to find Ipeak which can be found from voltage divided by total impedance of the circuit.
for (c) you know Z(=R+j(Xl-Xc) ) from this you find the phase difference.
 
  • #3
60
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ok
for part

b) Ipeak = Vpeak/ Z
but don't i need the value of frequency to calculate this?
because since the reactance of L anc C need the value, i need it here...
or can i assume that it's at resonance? Then Z= R :S

C) I read some more and i remembered that i could find the angle using tan = Xl - Xc/ R
but again, I need the frequency

is there something i'm missing here?
 
  • #4
245
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b) Yes you need frequency information. The supply frequency can be known from V(t)=1.414sin(1000t). Find frequency and then Z.
c) You are right.
 
  • #5
60
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oh i see now,
i solve for omega using that given equation
thank you so much!
 

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