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Voltage and Potential Energy

  1. Sep 4, 2016 #1
    1. The problem statement, all variables and given/known data
    When a -2C is moved from point A to B, the potential energy of the system increases by 10J. What is the voltage V(ab)?

    2. Relevant equations

    3. The attempt at a solution
    10=(-2)V, I thought the voltage was -5V but the correct answer is +5V. Could someone explain why this is?
  2. jcsd
  3. Sep 4, 2016 #2


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    Homework Helper
    Gold Member

    Vab is nothing but Va-Vb. In simple words, if you have a positive charge and a negative charge placed close to each other, you'll observe a gain in potential energy of the negative charge if it is moved away from the positive charge. Here, since the negative charge is gaining energy, point A must be at a higher potential (more +ve than B) than point B. Hence, Vab= +5V.
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