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Electrical Potential, Voltage, Work

  1. Aug 6, 2012 #1
    Hi guys,

    So my question is related to Electical Potential Eenrgy and Voltage. First off, I am using the Physics book by Cutnell, 8th Edition. If anyone would like to turn to the page I am on, it is page 570 or around there if you have the newer edition.

    So, they first relate Work by equation 19.2 as shown below, and then Voltage by equation 19.3. So i get that part, sorta.

    But when it comes to Voltage, as shown in equation 19.4, is Voltage (negative) Work divided by charge?

    in equation 19.2, they use EPEA-EPEB, but why not the other way around.
    Then 19.4 calcualtes Voltage by using EPEB-EPEA, but Work is now negative.

    equations.jpg

    So i guess my main question -- in 19.2, why is EPE calculated as the first point minus the second point, and not the other way around?
    The other question relates to Voltage and negative work? I've read the section twice now and it is still not sticking.

    Sorry if my question is complicated, I'll try to answer any questions you have about my question. :tongue:

    Thank you!
     
  2. jcsd
  3. Aug 6, 2012 #2

    Drakkith

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    Staff: Mentor

    You should probably type out the equations. Most people do not have your textbook.
     
  4. Aug 6, 2012 #3
    Not sure if the equations are showing in the original post, but here they are in case they are not showing up.

    bga493.jpg
     
  5. Aug 6, 2012 #4

    rcgldr

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    Homework Helper

    Voltage is the potential energy divided by charge. The change in voltage is related to work divided by charge.
     
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