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Finding the resistance of a solenoid?

  1. May 7, 2012 #1
    I have a solenoid with 180 turns, which is 10 cm long. It has a half core of magnets (which could be constituted as part iron core). The magnetic field strength was measured to be 0.004982 T inside the solenoid around the middle when 12v was run through it and 0.004512 without power running through it. To work out the theoretical magnetic field, I have to use Ampere's law:
    B=μ x N x I

    B = 8.75x10^-4(because of the iron core)x180x(current in amps)

    The problem is I don't have the current in amps.

    But I thought I could use Ohm's law:
    V= IR

    and changed it to

    I= V/R

    I need the resistance without measuring it, but I don't know how to get it.
    Last edited: May 7, 2012
  2. jcsd
  3. May 7, 2012 #2


    User Avatar

    Staff: Mentor

    Do you know the diameter of the wire, and the material it's made of? If so, try Googling for "resistivity."
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