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Homework Help: Gausses Law Question

  1. Nov 3, 2007 #1
    Electromag Question

    1. The problem statement, all variables and given/known data

    When the terminals of a 100V battery are connected to two large parallel horizontal plates 1 cm apart the electric field E between them has a magnitude of E=10^4 NC^-1, and is directed upward. Compute the force on the electron in the field and compare it with the weight of the electron.

    [charge on an electron = -1.6x10^-19, mass of electron =9.11x10^-31kg]

    If the electron were projected into the field with an initial horizontal velocity V0, find the equation of its trajectory of the form y=f(x) (take y verticle and x horizontal).

    3. The attempt at a solution

    I have a solution to the first part using the formula: F=qE, I found f = -1.6x10^-15.
    I then wored out the weight using w=mg, getting 8.94x10^-30 N. I compared this and explained that as F is vastly bigger than W the object will move upwards rather than downwards towards gravity.

    However I have no clue on how to do the second part, please help.
    Last edited: Nov 3, 2007
  2. jcsd
  3. Nov 3, 2007 #2


    User Avatar
    Science Advisor

    This is just like throwing a ball horizontally, and asking for the path it follows (except the electron "falls" up, because of the electric field). Just look up all those formulas from mechanics.
  4. Nov 4, 2007 #3
    So are you basically saying I should use the projetile motion formulas?
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