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Homework Help: Parallel plate conductor

  1. Feb 22, 2014 #1
    1. The problem statement, all variables and given/known data

    An electron is fired at a speed vo = 5.6 ✕ 10^6 m/s and at an angle θo = -40° between two parallel conducting plates that are D = 2.5 mm apart, as in Figure P16.66. The voltage difference between the plates is ΔV = 103 V.


    2. Relevant equations

    F = Eq

    E = V/d

    a = F/m

    3. The attempt at a solution

    I tried finding acceleration with (ΔV/D)(q/m) or 103/.0025 * 1.6e-19/9.11e-31

    I found Vy with 5.6e6sin(40)

    Then i used vyf^2 = vyo^2 + 2aΔy to solve for Δy

    then i subtracted my answer from .00125 m and got .54 mm, but the website says i'm off by more than 10%.

    I haven't tried part B yet because i could have acceleration wrong and that will just mess up both answers.
    Last edited: Feb 22, 2014
  2. jcsd
  3. Feb 22, 2014 #2


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    Gold Member

    Don't forget gravity, or at least check how it compares with the acceleration of the electric field.
    Write down equations, instead of narrating your calculations.
  4. Feb 22, 2014 #3
    The acceleration was something x 10^15 so i figured gravity was negligible.
  5. Feb 22, 2014 #4


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    Staff: Mentor

    Hi laurajean997. Welcome to Physics Forums.

    Can you show your attempt in a bit more detail? In particular, show the values that you obtained for the intermediate steps.
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