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Homework Help: Change in potential energy of the particle

  1. Jul 4, 2016 #1
    1. The problem statement, all variables and given/known data
    A particle with a charge of 2e moves between two points which have a potential difference of 75V. What is the change in potential energy of the particle?

    2. Relevant equations
    U = (75 V)(2e)

    3. The attempt at a solution

    When a particle with charge e moves through a potential difference of 1 volt, the change in potential energy is 1 eV. If the charge is some multiple of e—say Ne—the change in potential energy in electron volts is N times the potential difference in volts. Note: 1 eV = 1.602 x 10⁻¹⁹ J.

    Potential is potential energy per unit charge. We define the potential V at any point in an electric field as the potential energy U per unit charge associated with a test charge q₀ at that point:

    V = U/q₀
    U = Vq₀
    U = (75 V)(2e)
    U = 150 eV
    U = 150(1.602 x 10⁻¹⁹ J)
    U = 2.403×10⁻¹⁷ J

    Solution: U = 150 eV = 2.403×10⁻¹⁷ J

    just need to make sure if i did this correctly? or do i need todo anything else?

    Thank you
  2. jcsd
  3. Jul 4, 2016 #2


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    Homework Helper
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    2017 Award

    OK. But be sure you understand that you are not finding the potential energy U itself. You are calculating the change in potential energy ΔU. The appropriate relation would be written ΔU = q ΔV, where ΔV is the potential difference.
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