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Homework Help: Motion of Charges in E and B Fields

  1. May 4, 2012 #1
    1. The problem statement, all variables and given/known data
    Consider and electron being ejected from the surface of a heated filament at nearly zero speed. Through what potential difference must it be accelerated to achieve a speed of 8.4x10^6 m/s?

    2. Relevant equations
    I have found that the equation I should be using is 1/2mv^2=eΔV (where I believe ΔV is m/e?)

    3. The attempt at a solution
    No attempt finding the equation is the work I have done.
  2. jcsd
  3. May 4, 2012 #2


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    Hi Patrick! :smile:

    (try using the X2 button just above the Reply box :wink:)
    yes :smile:

    (but do you mean that you've worked out that this is the correct equation, or that you found it somewhere and it looks right? :confused:)
    no, ∆V is the voltage difference (electric potential difference)

    (V means voltage, ∆ means difference in)
  4. May 14, 2012 #3
    I have a question on this one...what would the mass be? You have the V and e correct but you don't have m??
  5. May 14, 2012 #4
    OR would the mass be just the standard electron mass at 9.11×10^-31 kg?
  6. May 15, 2012 #5


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    yup! :smile:
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