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Homework Help: Find the x-component of the magnetic force on the wire

  1. Feb 21, 2010 #1
    1. The problem statement, all variables and given/known data:
    A wire with a length of 29.0 cm lies along the z-axis and carries a current of 9.00 A in the +z-direction. The magnetic field is uniform and has components Bx = -0.204T, By = -0.968T, and Bz = -0.328 T

    2. Relevant equations
    1. Find the x-component of the magnetic force on the wire. Ans: 2.5N
    2. Find the y-component of the magnetic force on the wire Ans: -0.532N
    3. Find the z-component of the magnetic force on the wire
    4. What is the magnitude of the net magnetic force on the wire?

    3. The attempt at a solution.
    I solved question 1 and 2. But I don't fully understand why. For question 1 I used the force in the y direction and in 2 I used the force in the x direction. But why like that?
    For #3, I used the z direction force, and its not correct. So kind of confused.
  2. jcsd
  3. Feb 21, 2010 #2
    The force on a wire in magnetic field B is given by

    [tex] \vec{F_B} = I \vect L \times \vect B [/tex] where L is a vector that points in the direction of the current and magnitude the length of the wire.


    [tex] \vec{L} = 0.29k [/tex]
    [tex] \vec B = -2.04i-0.968j-0.328k [/tex]

    Compute the cross product using a determinant.
  4. Feb 21, 2010 #3
    Oh ok, kind of forgot myu calculus a bit. Read over my notes from Cal class, makes sense now. Thanks.
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