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Homework Help: Easy question on voltmeters

  1. Nov 2, 2008 #1
    1. The problem statement, all variables and given/known data

    For what external resistance is the voltmeter most accurate (a high resistance or a low resistance)? (given that the voltmeter is not ideal and does have an internal resistance not equal to infinity)

    2. Relevant equations

    3. The attempt at a solution

    On first thought i said that it would be when the external resistance is smallest seeing as the effect of the internal resistance should be smallest. But then again accuratelly measuring smaller values is supposed to be difficult....
  2. jcsd
  3. Nov 3, 2008 #2
    I won't give a direct answer.....

    Take two approaches -
    1 - look at websites for voltmeters and review spec sheets - what do you consider low vs high reistance - ranges vary by orders of magnitude. There will be an accuracy spec for each range, from this what do you conclude?

    2 - How does a voltmeter measure resistance? by sampling current or voltage? draw a circuit diagram of the voltmeter with the test load - be sure to include the the internal resistance of the voltmeter - if the voltmeters components are 1% accurate components, how much does the measurement change?
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