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Homework Help: Magnetic field

  1. Feb 26, 2006 #1
    Hi, I have this problem and I need some explanation and help to solve it:

    An electron is injected at t=0sec with a velocity of vo =(2*10^6 m/s) i into a region with parallel electric field E=(1500V/m)j and B=(-.2T)j,respectively.
    Calculate the subsequent motion.


    What I did is that I know that the motion will be a circular one.
    then I computed R =m*v/(q*B)
    Can I compute R this way since we have electric and magnetic fields together??

    Also How can I find the acceleration? when I do V2/R I dont get the right answer at the back of the textbook.

    Thank you
    B
     
  2. jcsd
  3. Feb 26, 2006 #2
    Since there's an electric field, the magnitude of it's velocity increases, so the radii will chage. You can plug the Lorentz force into Newton's 2nd law.
     
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