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Homework Help: Nonideal voltmeters

  1. Feb 1, 2005 #1
    Here is the question, for reference:

    I have two equations but am having trouble solving them for V, clearly by eliminating I

    E-(I*r)-(I*R_V)=0
    V_ab=E-(I*R)

    Any help would be appreciated, thanks.
     
  2. jcsd
  3. Feb 1, 2005 #2
    Nevermind, I got it, but the next problem is giving me a bit of trouble:

    If E = 7.5 volts and r = .45 ohms, find the minimum value of the voltmeter resistance R_V for which the voltmeter reading is within 1.0% of the emf of the battery.

    I am given the following equation to work with:

    E(1-(r/(r+R_V))
     
  4. Feb 1, 2005 #3
    Nevermind, got that too. Disregard this thread, heh.
     
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