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Homework Help: Accelerated electron through a circular path

  1. Jun 1, 2010 #1
    1. The problem statement, all variables and given/known data
    An Electron is accelerated through a potential difference of 5.0KV
    (i) Find it's velocity.
    (ii) It is then passed through a region of transverse magnetic field where it moves in a circular path of radius 0.20m. Find the magnititude of the field.
    (iii) Find the time taken to for the electron to complete one rotation.

    2. Relevant equations
    For (iii)
    Rotational KE = ½ Iw2
    max velocity = 3x10^(7)
    Magnitude of the field = 8.52x10^(-4)
    potential difference = 5.0kV
    radius = 0.20m
    t = ?

    3. The attempt at a solution
    (i) I got 3x10^(7)
    (ii) I got 8.52x10^(-4)
    (iii) I'm really not sure how to approach this question any hints in the right direction would be great.
  2. jcsd
  3. Jun 1, 2010 #2
    the magnetic field does not change the speed of the electron.
    so its velocity would be what u calculated in (i).

    then t = 2*pi*r/v.
    as simple as that.
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