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Homework Help: Kinetic Energy's Effect on Electron's Radius in Magnetic Field

  1. Apr 16, 2012 #1
    An electron moves in a circular orbit of radius r in a magnetic field. The electron moves in a path perpendicular to the magnetic field. If the kinetic energy of the electron is doubled, what is the new radius of its path?

    What formula would I use to go about this? Is this about mass spectrum? So I would go about using Fnet=ma, and then Fb (of a single charge) = mv^2/r.
    So Bvq = mv^2/r... then where?

    Please help! Test tomorrow! :(
  2. jcsd
  3. Apr 17, 2012 #2
    Sure, you're on the right track. Use that to solve for [itex]r[/itex] first. Then think about which quantity in the equation for the radius will change if the kinetic energy is doubled, and figure out how much it will be changed by.
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