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Homework Help: Mass Spectrometer Question #2

  1. Apr 8, 2007 #1
    1. The problem statement, all variables and given/known data
    A singly charged positive ion has a mass of 2.50 x 10^-26kg. After being accelerated through a potential difference of 250 V, the ion enters a magnetic field of 0.500 T, in a direction perpendicular to the field.

    2. Relevant equations
    Calculate the radius of the path of the ion in the field.

    3. The attempt at a solution
    Firstly, I drew this picture to try to help me with the problem:
    http://img411.imageshack.us/img411/4197/picxc7.jpg [Broken]

    I've tried to set Fm = Fe, therefore coming up with the derived equation of V=E/B, but I don't know E.

    I then tried to find the electric field by using the voltage, but I don't know the distance. (V=ED)

    I also tried setting Fm = Fc, getting Bqv = mv^2/r, and finally resulting in Bqr/v=m. I had B, q, and m, but I didn't have r and v.

    Thanks for reading.
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Apr 8, 2007 #2
    Try energy conservation
  4. Apr 8, 2007 #3
    :surprised You're a lifesaver.
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