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Voltage in a circuit

  1. May 16, 2012 #1
    Hello this is my first post here :)

    Please i would like to know why when we put a Voltage source in a circuit why for exemple a potencial difference appears on a resistance( I know a Voltage source has difference in potential created by difference in charges and an electrical field appears in the circuit so the electrons will flow) but why there's a potentiel difference over a resistance in a circuit and i saw on youtube that the potential difference over a resistance create the flow of charges? how come ? Thank you
  2. jcsd
  3. May 16, 2012 #2
    PS: i cant post the youtube link since i didnt reach 10 posts yet:P anyways if any one is interested the title is Resistance and its uploaded by april 1515... and i read several books they say the difference of potentiel creates electric field so the difference in potentiel over a resistance creates a field?
  4. May 16, 2012 #3
    Here's a link to the video:


    Hope that helps!
  5. May 16, 2012 #4
    exactly thanks:)
  6. May 16, 2012 #5
    plus if you read the book of Field Theory vy A.V. Bakshi it says : "Thus work done per unit charge in moving unit charge from B to A in the Field E is called potential difference between the point B and A" so who creates the field E and who does the work?
    Last edited: May 16, 2012
  7. May 17, 2012 #6


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    Staff: Mentor

    Hi tonyjk! http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]

    The battery causes its voltage to appear across whatever points the battery wires are connected to. If the wires are not connected anywhere, then they are actually connected across some air, so the battery's voltage appears across a volume of air. :smile:

    The volt is just another name for 1 Joule/coulomb; the Joule being a unit of work. So a 1V voltage source has performed one Joule of work once it has moved 1 coulomb of charge from one terminal of the voltage source to the other terminal. So if you wish to show that you know what you are talking about, you could refer to a 1.5V battery as a 1.5 Joule/coulomb cell. :wink:
    Last edited by a moderator: May 6, 2017
  8. May 17, 2012 #7
    okay i understand now more but the potential difference over a resistance is the same? it's also the work done by the electric field? and the difference of potential is it due to a difference of charges?( positive and negative?) so across the resistance there's difference of charges or what? thanks
    Last edited: May 17, 2012
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