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Lorentz force spectrometry

  1. Jul 15, 2013 #1
    If a particle of mass m and charge q (where q can be negative or positive, and the velocity should be positive if q is positive and negative if q is negative) is passed through an electric field of potential Vd, what is the velocity v of the particle?

    Or possibly this should be a vector problem? Maybe I need to specify some angles? If you'd take me through what's going on here I'd be grateful, and if there are some angles of incidence I should have given but didn't then please give them algebraic letters anyway and proceed.
  2. jcsd
  3. Jul 15, 2013 #2


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    Staff: Mentor

    What is the context of your question? Is this for schoolwork? What references are you using so far to understand the Lorentz force?
  4. Jul 15, 2013 #3
    No I'm asking this question for my own understanding. The topic is mass spectrometry and my reference so far is this document:

    http://www.whoi.edu/cms/files/Lecture6_2011_96624.pdf [Broken]

    Everything makes sense except for the velocity as a function of mass, V and charge expression. And in general, the problem I see with the whole thing is that it would appear to treat negatively charged particles the same way as positively charged particles (either that, or say that they have the same velocity).
    Last edited by a moderator: May 6, 2017
  5. Jul 17, 2013 #4
    My final goal is to figure out how, in a mass spectrometer, we can transform the time taken for each ion to reach the detector, into the mass/charge value for that ion.
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