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Motion of an electron in a Magentic Field

  1. Nov 24, 2009 #1
    1. The problem statement, all variables and given/known data
    Plot the motion of an electron in the x-y plane due to a magnetic field in the z plane. The initial position is at the origin. The initial velocity can be chosen at will.

    2. Relevant equations
    F = q(vXB)

    3. The attempt at a solution
    The program im using is Matlab. I tried plotting the motion using the following set of equations, but the motion was a spiral, not circular. Any pointers in the right direction would be much appreciated!
    (Vx is the velocity in the x direction, x is the position, etc..)


    Vx(i+1) = Vx(i) + w*(Vy(i)*B)*dt
    x(i+1) = x(i) + Vx(i)*dt

    Vy(i+1) = Vy(i) + w*( -Vx(i)*B)*dt
    y(i+1) = y(i) + Vy(i)*dt
  2. jcsd
  3. Nov 24, 2009 #2


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    Homework Helper

    It's probably spiral in MATLAB because of integration errors. It seems you think that the motion has to be circular because a magnetic field always applies a force perpendicular to the electron's motion, and you'd be right.
  4. Nov 24, 2009 #3
    Well as long as my equations are right then thats ok:smile:
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