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Homework Help: Advanced physics problems on electric fields.

  1. Feb 13, 2012 #1
    1. The problem statement, all variables and given/known data

    Secret Agent Jane Pond is testing out a new particle ray gun. She knows the particles in the ray have charge -2e and a mass of 50u. (u = atomic mass unit.) To determine the speed of the particles in the ray, Jane needs a region of uniform electric field. She takes two very large uniformly charged sheets with charge densities of ±σ , and arranges the sheets so that the positive sheet is horizontal and the negative sheet makes a 60° angle with the horizontal. She then shoots the particle ray through the region of space between the sheets, entering the region 1.0 mm vertically from the horizontal sheet and 4.0 mm horizontally to the side of the intersection point, with an initial velocity parallel to the intersection axis. (a) Find an expression for the net electric field at the entry point, ignoring edge effects. (i.e., you can treat the sheets as infinite.) Your answer should be in terms of σ and ε0. (b) Which sheet will the particle ray ultimately strike? Explain how you know. (c) Jane finds that the location where the ray hits the sheet is 5.0 cm from the entry edge of the sheet. If σ=25 nC/m2, what is the initial speed of the particles in the ray?
    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Feb 13, 2012 #2

    Simon Bridge

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    Homework Helper

    Welcome to PF.
    In order for us to help you, you need to have an attempt at the problem or at least tell us about how you are thinking about it. That way we can tailor the assistance to what you actually need instead of guessing.
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