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Magnetic field of earth, how much current needed to cancel it

  1. Jul 7, 2012 #1
    1. The problem statement, all variables and given/known data

    Solenoid consists of a hollow tube of length 5 meters and around which 1000 turns of wire are wrapped.?

    Current I flowing in the wire generates a magnetic field whose direction is given by the right hand rule. It can be shown the magnetic field in a long narrow tube is uniform and given by B(Tesla) =1.26E-6 N I(amp) where N is number of wire loops/meter. Assuming the solenoid is aligned along the Earth's magnetic field,how much current is needed to cancel the Earth's field?

    Solenoid cross section
    ______________________current out of page
    ---->B
    ______________________ current into page
    earth's magnetic field is 10^-4 Tesla

    2. Relevant equations



    3 The attempt at a solution
    N=1000/5=200
    I=(10^-4)/(1.26E-6)(200)
    I=0.396 A

    Is that all there is to it? or am I missing another step
     
    Last edited: Jul 7, 2012
  2. jcsd
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