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Homework Help: Right Hand Rule

  1. May 19, 2009 #1


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    1. The problem statement, all variables and given/known data
    For this given diagram, determine whether the particle is a proton or an electron.

    2. The attempt at a solution
    Considering at the point where it enters the material.
    Using RHR, Velocity is downwards (First Finger), Field is outwards (Middle Finger), Thumb points left but the force is supposed to be to the right so it's an electron.

    3. The Problem encountered
    The answer says that it's a proton but how can that be. Am I doing my RHR correctly? Can someone explain how it works. Thanks in advance.
  2. jcsd
  3. May 19, 2009 #2


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    Why is force supposed to be towards the right? You correctly found that v x B points left at the point where the particle enters the field. The force is F = q(v x B), so if the particle is positively charged, the force will be towards the left and the particle will be deflected towards the left. That's what happens in the picture, so it must be a proton. If q was negative, it would have been deflected towards the right.
  4. May 19, 2009 #3


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    For F=Bil, which fingers represent which part?

    Is it first finger current, middle finger field and thumb is force?
  5. May 19, 2009 #4


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