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Can potential energy be in the unit of Volts?

  1. Mar 10, 2010 #1
    In my teacher gave us homework on electricity. One of the questions ask "what is the potential energy of the pair of charges? Answer in the units of V." Is that an error, or is there a way to convert Joules to Volts?
  2. jcsd
  3. Mar 10, 2010 #2
    Electric Potential (volts) is the potential energy per unit charge. So the potential energy of a charge q in a region of space with electric potential V is U = qV.
  4. Mar 10, 2010 #3
    But doesn't that equation give the energy in joules?
  5. Mar 10, 2010 #4
    LOOK at the equation!!!!!!!!!!!!!!!!!!
  6. Mar 10, 2010 #5
    Exactly. charge, q, is in coulomb. Electric potential is in volts. coulomb * volts = joules. So you LOOK at the equation!
  7. Mar 10, 2010 #6
    you don't yet understand what you are looking at...getting angry with those attempting to get you to solve your problem, like me, will avail you nothing...I am trying to get you to THINK....not get angry....

    Let's try it this way...suppose I said to you distance equals verlocity times time...d = vt, and asked you how long it will take to move a given distance at a given velocity.....
    how would you approach that??

    Use the same approach to your problem...

    Also, this is NOT the forum for homework questions....
  8. Mar 10, 2010 #7
    I understand what you are saying, t = d/v. But I am looking for potential energy not electric potential.
  9. Mar 10, 2010 #8
  10. Mar 10, 2010 #9
    You still haven't answered the question. How can electric potential energy be in volts, if electric potential is in volts?
  11. Mar 10, 2010 #10


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    Strictly speaking you can't. There is no "correct" way to express energy in units of volts in the SI system (Volt is a 'inoffically' a base unit, Joule is a derived unit).
    However, since they in this case only differ by e it is not at all unusual for people to talk about potential energy in volts.

    Also, there IS a way to write this while still using the right units (which is what some people do in research papers and other "offical" documents).
    You should be able to figure it out by looking at the equation (which I suspect is what Naty1 is refering to)
  12. Mar 10, 2010 #11
    How much electrical energy is stored in a 2200-milliamp-hour rechargeable NiMH battery?

    Bob S
  13. Mar 10, 2010 #12


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    Hi miamirulz29! :smile:

    (btw, "joules" and "volts" have small intital letters :wink:)

    I agree with you …

    potential energy is in joules …

    electric potential is potential energy per charge, so is in joules per coulomb, or volts.

    (I've no idea what everyone else is hinting at :redface:)
  14. Mar 10, 2010 #13
    I just found it that there was a typo in the problem. The teacher meant to say joules not volts.
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