Ohms law??

Discussion in 'Homework Help' started by Hotfingers, Mar 29, 2015.

  1. Hotfingers

    Thread Starter New Member

    Mar 29, 2015
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    Hi I'm new to this site and would be grateful for a bit help with some home work exam to follow shortly...if I have the resistance and the csa how do I work out the length?... Thanks guys
     
  2. Papabravo

    Expert

    Feb 24, 2006
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    What is the csa?
     
  3. Treeman

    Member

    May 22, 2014
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    Cross sectional area PB. I guess we talkin wire diameters. My answer would be find the equations that use these known measurements and substitute where required.
    R=(resistivity x length) / csa
     
  4. Papabravo

    Expert

    Feb 24, 2006
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    Last edited: Mar 29, 2015
  5. WBahn

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    Mar 31, 2012
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    So to use that equation you need three of the four parameters. You apparently only have two. You also need to know the resistivity. Doesn't it make sense that the length of aluminum wire is going to different than length of copper or the length of steel?

    @Hotfingers : Do you have either the resistivity or at least the material that the wire is made out of?
     
  6. Papabravo

    Expert

    Feb 24, 2006
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    I missed the part about aluminum. Where did that come from?
    Nevermind, it was just an example to show different materials have different resitivity.
     
  7. Treeman

    Member

    May 22, 2014
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    Treeman was being helpful as much as he could. I assumed there was more info to reveal - this seems to be the case often.
     
  8. WBahn

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    Mar 31, 2012
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    No problem there. I didn't realize until after I had posted that the two quotes in my response were from different people, so I went back and added the note to the TS.
     
    Treeman likes this.
  9. Hotfingers

    Thread Starter New Member

    Mar 29, 2015
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    Thanks for reply,s guys will continue with the homework,cheers
     
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