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Homework Help: Force on a Wire In Uniform Magnetic Field

  1. Oct 11, 2012 #1
    1. The problem statement, all variables and given/known data
    A long wire lying along the x-axis carries a current of 2.60 A in the +x direction. There is a uniform magnetic field present, given by B=0.003i + 0.004j + 0.002k, where i, j, k are the unit vectors along the cartesian coordinate axes') in units of Tesla. Calculate the y-component of the magnetic force acting on a segment of wire of length L = 17.5 cm.

    2. Relevant equations

    3. The attempt at a solution

    I tried using the formula F=ILBsin@
    where F=force, I=Current, B=magnetic field in tesla, sin@=1 (b/c y axis is perpendicular to x so @=90 degrees).
    but that didn't work...I don't really know how to make sense of the B field equation?

  2. jcsd
  3. Oct 12, 2012 #2


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    hi bmb2009! :smile:

    (have a theta: θ … or pick it up from the Quick Symbols box to the right of the Reply box :wink:)
    no, the θ in ILBsinθ is the angle between I and B

    (the force F = LI x B is perpendicular to both I and B)

    that gives you the magnitude of F, then find the component in the y direction :wink:
  4. Oct 12, 2012 #3
    Can you be more thorough? Like i have no idea where to start our teacher never went over anything close to something with a b field given as components... so I Don't know how to find an angle from it and even if I did I would know how to find the Y component afterwards..
  5. Oct 12, 2012 #4
    I tried:

    since the B field and current are parallel in the x direction the f=0
    so the magnitude of the force is the force from the y and z components which i plugged in to get a number but how would you calculate of Y component without any more information?
  6. Oct 12, 2012 #5


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    show us your cross product calculations for the total F :smile:
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