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Homework Help: Current in a soloneid

  1. Sep 29, 2005 #1

    My Question:

    A 50.0-cm long solenoid 1.25cm in diameter is to produce a field of 0.385 T at its center. How much current should the solenoid carry if it has 975 turns of the wire?

    I know that I have to use this equation:

    B = \mu _0 nI

    where i'm stuck at is with the length do I used the how long it is with the diameter or do i just ignore the diameter :confused:

    please help

    Thank You :smile:
  2. jcsd
  3. Sep 30, 2005 #2


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    Homework Helper

    The formula you have written is for a long solenoid such that L >>R, to insure this, I think the dimeter is given, otherwise you have to use general formula for the field.
    In this formula 'n' is the number of turns per unit length n = N/L.
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