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Homework Help: I cant understand voltage

  1. Feb 18, 2009 #1
    I'm doing AS-level physics at the moment and we have moved onto circuits, current, etc. I feel a bit of an idiot but i cannot seem to describe in fully what voltage is. this is mainly because i dont really know. i understand that it represents the potential difference in a circuit, but i have limited understanding of that too. i can remember equations etc, regarding voltage, (V=IR, V=P/I, etc), i just cannot explain it if a question asks me too. any help would be appreciated.

    thank you

    My try at explaining it

    It has some thing to do with the pd of a circuit which when all the the pd across a circuit is combined it is the same as the electromotive force provided by the power cell
  2. jcsd
  3. Feb 18, 2009 #2
    If you can understand what gravitational potential is you can then understand what electrical potential is. Let's say you want to lift an object of mass [tex]m[/tex] to height [tex]h[/tex]. Now when you start to lift the object, gravitation starts to pull it down. If you want to beat the gravitiy you must do certain amount of work to get [tex]m[/tex] to [tex]h[/tex].

    Now electric potential is basically the same but the gravitation can change directions depending on the particles's charge. Now you have to plates one of them has a charge of [tex]Q[/tex] and the other [tex]-Q[/tex] and their distance is [tex]h[/tex]. If you want to move a particle [tex]q[/tex] from [tex]-Q[/tex] to [tex]Q[/tex], you need to do certain amount of work. [tex]q[/tex] is positively charged.

    Does that help?
  4. Feb 18, 2009 #3
    so are you saying that the potential difference, (i.e. voltage), is the potential energy that will be needed to move a charged carrier to different points around a circuit?
  5. Feb 18, 2009 #4
    Yup, voltage = charge potential. And charge is polarized already, which comes in handy.
  6. Feb 18, 2009 #5
  7. Feb 18, 2009 #6


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    voltage = energy per charge

    Hi v! :smile:

    All the electric units are connected to each other and to ordinary units …

    for example 1 volt = 1 joule per coulomb …

    voltage = energy per charge …

    in other words, the voltage between two points tells you how much energy you get if you move a charge across. :smile:
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