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Homework Help: Diameter and resistance

  1. Feb 14, 2009 #1
    1. The problem statement, all variables and given/known data

    If 46 m of nichrome wire is to have a resistance of 12.0 Ω at 20°C, what diameter wire should be used?

    2. Relevant equations

    R=[tex]\rho[/tex](L/A)

    3. The attempt at a solution

    I tried and I got 2.1. The [tex]\rho[/tex] of nichrome is 108e-8
     
  2. jcsd
  3. Feb 14, 2009 #2
    First solve for the variable you are looking for and put it on one side. Keep your knowns on the other side. Remember that A stands for area, and area is related to wire diameter.

    I am online for a bit, so give it a go. DON'T FORGET YOU UNITS!
     
  4. Feb 14, 2009 #3
    ok yeah i got 2.3 mm. after i figured out A. I figured out diameter doing A=1/4pi(dsquared)
     
  5. Feb 14, 2009 #4
    ok i got it right. thanks!
     
  6. Feb 14, 2009 #5
    Good for you!
     
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