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Homework Help: Charged particle in a cloud chamber?

  1. Jun 2, 2010 #1
    1. The problem statement, all variables and given/known data
    when a charged particle enters a magnetic field in a cloud chamber, why does it move in a circular path instead of straight line? I have no idea why. please help

    2. Relevant equations

    3. The attempt at a solution
    it has something to do with the r changing? as I said, I have no idea.
  2. jcsd
  3. Jun 2, 2010 #2
    Do you know the rules governing moving charges in uniform B fields and how the direction of the Force is oriented? Some use the right hand rule? Is this familiar?
  4. Jun 3, 2010 #3
    As pgardn mentions above, a magnetic field interacts with a charged particle in quite a peculiar way. Similar to a ball being spun on a string, the magnetic field exerts a centripetal force to the component of the charge's velocity that is perpendicular to the field (whew. that sounded like a lot to digest!). What this basically means is that the magnetic force exerted on the charge always alters the charge's path, making it move in a circular path instead of a straight line.
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