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Potential difference between two points

  1. Oct 13, 2008 #1
    we know the current flow only when there is a potential difference between two points.consider the point A and B in the file attached ,both A and B are at same potential then why the current flow between them

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    Last edited: Oct 13, 2008
  2. jcsd
  3. Oct 13, 2008 #2


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    Re: potential

    Your first statement is wrong- you do NOT have to have a potential difference between two points in order to have electricity flow between them. Think of electricity as water flowing. "Potential difference" corresponds to different heights. Of course, water flows from higher to lower but you certainly can have water flowing along a flat area: the flow downhill before the flat section "pushes" the water ahead of it.
  4. Oct 13, 2008 #3


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    Hi nikhilthunder! :smile:

    (I flow, you flow, we flow, they flow, he flows, she flows, current flows :wink:)

    hmm … good question …

    any wire has a very very small resistance (which we usually ignore) …

    so by Kirchhoff's rules there's a very small potential drop between A and B …

    the current flows because of that potential difference. :smile:
    Last edited: Oct 13, 2008
  5. Oct 13, 2008 #4


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    Re: potential

    A potential difference is required for current to flow. In this case, the potential difference exists between the positive and negative terminals of the battery. This potential difference creates a current flow once a complete path is established between the terminals. Points A and B have current flowing through them but very little voltage drop due to the wire resistance (and no voltage drop if an ideal wire is assumed). With or without a local potential difference between points A and B, current still flows through them since the source current entering point A must equal the current exiting point A (conservation of energy or KCL). The same goes for point B.

  6. Oct 13, 2008 #5
    Re: potential

    But the current would flow without said potential difference if the resistance were zero. It flows with or without said PD, but the resistance, plus the sum of all other resistances determines the magnitude of current, as long as the power source maintains a constant voltage.

    The overall current flows because of the energy conversion taking place inside the battery. The distribution of various resistances around the loop determine the magnitude of the current, and the division of voltage.

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