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Homework Help: Electric Field and Magnetic Field

  1. Apr 20, 2009 #1
    1. The problem statement, all variables and given/known data

    A 6.45 uC particle moves through a region of space where an electric field of magnitude 1220 N/C points in the positive direction, and a magnetic field of magnitude 1.19 T points in the positive z direction. If the net force acting on the particle is 6.45E-3 N in the positive direction, calculate the magnitude of the particle's velocity. Assume the particle's velocity is in the x-y plane.

    2. Relevant equations

    3. The attempt at a solution
    This is what I did:
    using F=qE: (6.45 e-6 C)(1220N/C)= 0.00787 N

    Then using V=...
    : (1/1.19T)(1220N/C - 6.45 E-3/6.45 e-6)= 184.8 m/s

    BUT it keeps telling me my answer is wrong... do I have to put it in the negative direction?
  2. jcsd
  3. Apr 20, 2009 #2
    Where does your second equation come from? If we let the "positive direction" be the x-direction, which direction is the velocity pointing in?
  4. Apr 20, 2009 #3
    The velocity will point in the negative Y direction according to the right hand rule.

    The equation comes from:

    netForce= qE-qvB

    And when you plug all the values in i keep getting: 184.8 m/s but my computer says it is wrong.
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