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Homework Help: Calculating Resistance

  1. Sep 15, 2010 #1
    1. The problem statement, all variables and given/known data
    A heart pacemaker is designed to operate at 60 beats/min using a 4.0uF capacitor. What value of resistance should be used if the pacemaker is to fire when the voltage reaches 63 percent of maximum?


    2. Relevant equations



    3. The attempt at a solution

    0.63 x (4/1000) x 60
    I don't know if this method is right though?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Sep 15, 2010 #2

    Delphi51

    User Avatar
    Homework Helper

    The 63% is not a random choice; it is the standard for the "time constant" idea. You can look it up in Wikipedia if it isn't handy in your text book. http://en.wikipedia.org/wiki/Time_constant, fifth paragraph.

    So, you need a formula for the time constant of a capacitor to solve this problem.
     
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