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Homework Help: Magnetism and currents

  1. Apr 8, 2007 #1
    1. The problem statement, all variables and given/known data

    A compass needle points 20 degrees E of N outdoors. However, when it is placed 8.0 cm to the east of a vertical wire inside a building, it points 55 degrees E of N. What is the magnitude and direction of the current in the wire?
    The Earth's field there is 0.50 x 10^ -4 T and is horizontal.

    2. Relevant equations

    I'm thinking I'll need to use B = ( u I ) / (2 r pi) and something involving vectors...

    3. The attempt at a solution

    I really don't even know where to begin with the setup for problem. Do I start with the angles to find a vector sum of something? I just have no idea, sorry. Someone please help walk me through it.
  2. jcsd
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