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Homework Help: Torque acting on a coil?

  1. Aug 6, 2010 #1
    1. The problem statement, all variables and given/known data
    A rectangular coil consists of 25 turns of wire forming a square 4cm each side. By considering the force on a current-carrying straight wire, calculate the torque acting on the coil when the normal is at 30 degrees to a magnetic field of 0.8T and 12 A are flowing.

    2. Relevant equations

    t = ucrossB

    F = IlcrossB

    3. The attempt at a solution

    Umm I am a bit stuck with this as I do now know why I am meant to be using the force acting on the current carrying wire. I thought I could just use the t = ucrossB forumla in the form:

    t = ubsintheta

    where u = IA

    However this clearly isnt correct so I am looking for some help! Thanks
  2. jcsd
  3. Aug 7, 2010 #2


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    Homework Helper

    Torque τ = ΝΒΙΑsin(θ)
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