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Resistance of cut wires

  1. Jan 23, 2008 #1
    I need help with one of my Physics homework problems please!

    A certain copper wire has a resistance of 10.0 Ohm. At what point along its length must the wire be cut so that the resistance of one piece is 4.0 times the resistance of the other? What is the resistance of each piece?

    I worked it out and got that R=2 Ohm, and so the other piece, 4R, has to be equal to 8 Ohm. I used the equation for resistivity, R= rho*L/A using 4R in the place of R and solved for L. I replaced this back into the original equation but end up in a loop, with R=2. I have no idea what I'm doing wrong; can anyone please help?!
  2. jcsd
  3. Jan 23, 2008 #2

    Ben Niehoff

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    You need to use the fact that L1 + L2 = Ltotal.
  4. Jan 23, 2008 #3
    I did that on my second attempt to the problem but to no avail because I do not know when to use the "L1+L2" equation and the "Ltotal"
  5. Jan 23, 2008 #4


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    Consider it as a proportion.
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