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Homework Help: How many elementary charges does this particle carry?

  1. May 12, 2008 #1
    1. A force of 9.2x10-14 acts on an unknown particle that travels at 2.40x106 m/s into a magnetic field of 4.8x10-2 T. How many elementary charges does this particle carry?
    I've used Fm=qvB and found q=Fm/vB and got an answer of q=7.986 x10-19 C. I'm not sure where to go from here. I assume I have to divide by the elementary charge... but I don't know what that is. Haha.

    2. An alpha particle with a charge of 3.20x10-19 C and a mass of 6.65 x10-27 kg is travelling at 5.0 x106 m/s. When it enters a magnetic field of 6.4 x10-2 T, a magnetic force provides the centripetal force for the alpha particle. The centripetal force causes the alpha particle to travel in a circular path. Calculate the radius of the circular path.
    Do I simply use the equation r=(mv)/(qB)?
  2. jcsd
  3. May 12, 2008 #2


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    The elementary charge is the same as the magnitude of the charge of an electron, about 1.602×10-19 C.

    Sounds good to me :approve:
    Last edited: May 12, 2008
  4. May 12, 2008 #3


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    1. the charge on an electron is -1.602 176 487 × 10–19 C

    2. Yes, thats the correct formula.
  5. May 12, 2008 #4
    Thanks! :smile:
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