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Homework Help: Potentiometer problem

  1. May 1, 2015 #1
    1. The problem statement, all variables and given/known data
    A 3-V battery of internal resistance 1Ω is joined to a sliding wire of length 100 cm and resistance 5 Ω . A voltmeter , which takes negligible current , is connected across 60 cm length of the wire . (a) What is the reading of the voltmeter ? (b) If the reistance of the voltmeter were 150 Ω , then what would have been its reading ?

    2. Relevant equations

    3. The attempt at a solution



    V=0.5 x 5



    Reading= .025x60=1.5 volt

    I am not getting second part .
  2. jcsd
  3. May 1, 2015 #2


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    Staff: Mentor

    What have you tried? Have you drawn the circuit? Can you post it?
  4. May 2, 2015 #3


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    Homework Helper
    Gold Member

    Well split the wire into two parts (60 cm and 40 cm) and convert the circuit into lumped resistors..It'll get simple..
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