Capacitive Reactance formula with DC applied

Discussion in 'General Electronics Chat' started by massive, May 17, 2010.

  1. massive

    Thread Starter Member

    May 7, 2010
    20
    2
    Hi,

    If DC is applied to a capacitor , can the Xc formula also apply, minus the " frequency " component ..??

    Xc = 1 /(2*pi*f*C ) , remove f , becomes ; Xc = 1 /(2*pi*C ) ,

    for DC , presenting an open circuit at maximum Ohms .
    Ive calculated some μF measurements and they come out ,way into the MegOhm range ,so is it normal to utilise this idea ?.
     
  2. Bychon

    Member

    Mar 12, 2010
    469
    41
    The frequency still applies, and it is zero.

    and, No, it is not normal to utilize faulty formulas.
     
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  3. dsp_redux

    Active Member

    Apr 11, 2009
    182
    5
    In DC, you suppose the frequency to tend towards 0. Knowing that,
    X_C = \frac{1}{2\pi f C} |_{f\rightarrow 0} = \infty
    That's why in a DC analysis, you can pretend that capacitors are open-circuits.
     
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