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Homework Help: Magnitude and direction of induced current with magnetic field

  1. Feb 26, 2010 #1
    1. The problem statement, all variables and given/known data
    A conducting rod whose length is 25 cm is placed on a U-shaped metal wire that has a resistance of 8 ohm. The wire and rod are placed in the plane of the paper. A constant magnetic field of strength 0.40 T is applied out of the paper. An applied force moves the rod to the left with a constant speed of 6.0 m/s. What is the magnitude and direction of the induced current in the wire?

    2. Relevant equations
    Fwire = iLB
    I = V/R
    F = qvB

    3. The attempt at a solution
    I don't understand how to solve for the current. Is there a relationship between velocity and something else here that can help me solve for it? I have the length (.25m) and B field (.40T), so if I knew current I could solve for F. I also don't know how to find q of the conducting rod.

    The figure is attached. Thanks!

    Attached Files:

  2. jcsd
  3. Mar 1, 2010 #2
    Can anyone help me with this problem? Thanks!
  4. Mar 1, 2010 #3
    Do you know faraday's law? Remember that flux is [itex]\int \int B \cdot da[/tex]. The negative time derivative of flux will give you EMF (or voltage).
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