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How the current changes?

  1. Jun 30, 2009 #1
    1. The problem statement, all variables and given/known data
    A capacitor and inductor are connected in series to an AC generator. As the generator’s frequency is increased, the current in the capacitor

    A. increases

    B: decreases

    C: does not change

    D: can't answer this question due to no enough information.


    2. Relevant equations
    The impedance in the LC circuit is Z = │ωL- 1/ωC│
    Current I = V/Z


    3. The attempt at a solution
    If ωL > 1/ωC, then then ω increases, Z also increases, and current will decrease.
    If ωL < 1/ωC, then then ω increases, Z decreases, and current will increase.
    So the answer to this question is D.

    Is the above answer right?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jun 30, 2009 #2

    vk6kro

    User Avatar
    Science Advisor

    E: goes up then goes down.
    Not a fair question if the right answer is not included.

    A series tune circuit becomes low impedance at resonance, so the current goes up when the frequency equals the resonant frequency. Above or below that frequency, the current is less than at resonance.
     
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