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Homework Help: AC Voltage output across Resistor

  1. Jun 10, 2010 #1
    1. The problem statement, all variables and given/known data
    For the circuit below (attached) plot the amplitude of AC voltage across resistor as a function of the angular frequency of the ac source.

    2. Relevant equations
    ZR = R

    3. The attempt at a solution
    I'm not really sure about any of this. Across the resistor, the complex impredence is just R and so has no dependence on the angular frequency, but just plotting a stright line with amplitude IR can't be worth 5 marks (which is the marks for this question). Can someone explain this to me?

    Attached Files:

  2. jcsd
  3. Jun 10, 2010 #2


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    The current I varies with frequency.
  4. Jun 11, 2010 #3
    the L & C impedances vary with frequency.
    So, the voltage across the resistor should also vary as it is in series with the L-C combination.

    Find out the total impedance of the parallel combination of L & C (which is a function of w).
    Now R is in series with this combo-impedance.
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