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Calculate the Resistance of the RC circuit so that LED just stays on

  1. Jun 25, 2014 #1
    In a simple series circuit there is a 12V supply battery, 12μ6 F capacitor, a Resistor, and a 2v drop LED with an imax of 30mA. frequency is 10Hz
    Calculate the resistance of the resistor so that the LED just stays on.

    2. Relevant equations
    Resistance of Capacitor Xc = 1/2∏fC
    P=VI
    V=IR
    Impedence = √R^2+Xc^2



    3. The attempt at a solution

    Xc = 1/2∏x10x12x10^6
    =1326.3 Ω
    P=vxI
    P = 12 x 0.03A
    =0.36w

    i have no idea what else to do ! any help would be greatly appreciated please please please
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jun 27, 2014 #2

    rude man

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    A battery with 10 Hz? That's a new one on me.
     
  4. Jun 29, 2014 #3

    BvU

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    So, is Rhian (PS: welcome to PF) out of trouble now ?
     
  5. Jun 30, 2014 #4

    rude man

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    He/she doesn't seem interested in pursuing this fascinating ac battery problem, all the 'please pleases' notwithstanding ...
     
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