Magnetic force/field problem

  1. Dec 4, 2007 #1
    1. The problem statement, all variables and given/known data

    A wire extends horizontally from east to west. The mass of its meter is (0.18)g and it carries a current of (1)A. If the wire is in a magnetic filed (0.5)T that heads horizontally upwards, determine the least current that makes the magnetic force equal the wire weight

    2. Relevant equations

    F = BIl sin θ

    3. The attempt at a solution

    at first i dont understand what does "heads horizontally upwards" means so this is where i end up:

    mg = BIl sin θ
    (0.18E-3) x 10 = 0.5x1x1 sin θ
    θ = sin^-1(1.8E-3/0.5)
    θ = 0.2
  2. jcsd
  3. Dec 4, 2007 #2


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    Homework Helper

    I think horizontally upwards means perpendicular to the wire(direction of the current)
  4. Dec 5, 2007 #3
    You mean..

    BIl = mg
    0.5 I = 1.8E-3
    I = 0.0036 A ?
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