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Why does the current increase when the potential differene stays constant?

  1. Feb 12, 2009 #1
    A specimen has a potential difference applied, which remains constant throughout. The current through the specimen increases substantially though. Why does it increase?

    Is this to do with the temperature of the wire increasing and so resistance decreases and the current therefore increases. But the potential difference won't be affected as it is constant in voltage.

    Is this right at all? Or totally wrong?

    Many Thanks!
     
  2. jcsd
  3. Feb 12, 2009 #2
    You're saying the temperature dependency backwards. If the temp of a metal wire increases then the resistance would increase.

    To say that you're testing a specimen isn't really enough information. It doesn't sound clear whether the object under test might contain any switches or fuses or diodes, etc., or is able to be stretched into a new shape, or it's chemical composition is being altered, etc. Is it known to be simply a metal wire of constant dimensions? Are you expected to determine whether or not it is a metal wire?
     
    Last edited: Feb 12, 2009
  4. Feb 12, 2009 #3
    Sorry, no it doesn't contain any switches etc. but is just a piece of metal wire.

    So as the temperature in the wire increases, the resistance also increases. But how does this make the current increase if the voltage is constant?

    Thanks.
     
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