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Calculate the inductance of a coil of wire

  1. Mar 19, 2013 #1
    1. The problem statement, all variables and given/known data

    Calculate the inductance (SI units: Henries) of a coil of wire having a loop diameter of 0.5 cm and coil length of 10 cm. The wire has 1000 loops per meter.

    2. Relevant equations

    I think I can use this equation:
    L= μₒAN² / x, x = length of wire, μₒ = 4π*10^-7 Tm/A
    A = πr^2

    3. The attempt at a solution

    L= μₒ(πr^2)N² / x
    = μₒ(π(0.0025 m)^2)*(1000^2) / 0.1 m
    = 7.85 * 10^-5 H

    But apparently on my homework assignment that is wrong. Am I using the wrong formula?

    Edit: fixed units
    Last edited: Mar 19, 2013
  2. jcsd
  3. Mar 19, 2013 #2


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    Staff: Mentor

    Take a closer look at your value for N.
  4. Mar 19, 2013 #3
    @ gneill: I'm not sure if I'm thinking about this correctly but since I was given 1000 loops per meter, would I have to multiply this by the length (0.1 m) in order to just get the number of loops (N)?
  5. Mar 19, 2013 #4


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    Staff: Mentor

    That would be logical, right?
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