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Homework Help: Solenoid produces a magnetic field help

  1. Feb 3, 2008 #1
    1. A solenoid is 0.20 m long and consists of 100 turns of wire. At its center, the solenoid produces a magnetic field with a strength of 1.5 mT. Find the current in the coil.




    2. L be the length of the solenoid = 0.2m

    N be the number of turns = 100

    B be the magnetic field = 1.5 mT = 1.5 x 10-3 T

    I be the current in the coil in ampere

    μ be the permeability in air = 4 π x 10-7 H/m



    in a close circuit magnetic field



    B = μNI / L




    3. So, I = BL / μN

    = (1.5x10-3 x 0.2) / (4 π x 10-7 x 100)

    = 3 x 10-3 / 1256.637061 x 10-7

    = (3/1256.637061) x 104

    = 23.87324147 A

    ( Ans)

     
  2. jcsd
  3. Feb 3, 2008 #2
    Were you looking for a correct? It's correct.
     
  4. Feb 3, 2008 #3
    Yes, I was. And it really is? Yes!
     
  5. Feb 3, 2008 #4
    Well, technically, it isn't because the derivation you used assumes an infinite solenoid. :p

    It is what your professor/teacher would be looking for though. :)
     
  6. Feb 6, 2008 #5
    Given that,
    L = 0.20m, n = 100 turns, B = 1.5 x 10 ^-6 T
    have I = B/μo . l

    = 1.5 x 10^ -6 x 0.20/4 x 3.14 x 10 ^-7

    =0.024 x 10 A

    =2.4 10 ^-2 A
     
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