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Ammeter Voltmeter problem

  1. Apr 12, 2009 #1
    1. The problem statement, all variables and given/known data

    A circuit you're building needs a voltmeter that goes from 0 to a full-scale reading of 5.0 V. Unfortunately, the only meter in the storeroom is an ammeter that goes from 0 to a full-scale reading of 500 microA. It is possible to use this meter to measure voltages by putting in a measuring circuit as shown in the figure. (Figure attached)
    What value of R must you use so that the meter will go to full scale when the potential difference Delta V is 5.0 V? Assume that the ammeter is ideal.

    2. Relevant equations

    I = VR

    3. The attempt at a solution
     

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  3. Apr 12, 2009 #2

    rl.bhat

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    Re: Ammeter/Voltmeter

    When you connect the ammeter with a high resistance R in series across a measuring circuit, the current in the ammeter should be 500 mA. Delta V is given, Find R.
     
  4. Apr 12, 2009 #3
    Re: Ammeter/Voltmeter

    Delta V = IR
    I = 500 microA = 500*10^-6 A
    Delta V = 5 V
    R = V/I = 5 V/(500*10^-6 A) = 1*10^4 Ohm

    Is this correct?
     
  5. Apr 12, 2009 #4

    rl.bhat

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    Re: Ammeter/Voltmeter

    Yes.
     
  6. Apr 12, 2009 #5
    Re: Ammeter/Voltmeter

    I appreciate it.
     
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