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Electron and parallel plate question >

  1. Jan 23, 2009 #1
    electron and parallel plate question >:(

    1. The problem statement, all variables and given/known data
    The diagram below shows an electron entering the region between the parallel plates of a cathode ray tube. The electron has an initial velocity of 4.8x10^7 m/s horizontally and enters the exact middle point between the plates. The electric field intensity between the playes is 3.70x10^4 N/C upward. How far below the point midway between the plates will the electron strike the screen at point P?

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    2. Relevant equations

    This is my first time trying this and I have no clue how to approach this questions. Could someone direct my in the right way please?
     
  2. jcsd
  3. Jan 23, 2009 #2

    rl.bhat

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    Homework Helper

    Re: electron and parallel plate question >:(

    Electron behaves like a projectile.Since the direction of the electric field is upwards, the horizontal velocity remains the same. Electric field accelerates the electron in the downward direction. Find the acceleration. Range is given. Find the time taken by the electron to reach the screen. Knowing the acceleration and time find the distance travelled by the electron in the down ward direction.
     
  4. Jan 23, 2009 #3

    berkeman

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    Staff: Mentor

    Re: electron and parallel plate question >:(

    The units of Electric Field are V/m, so that should give you a hint for how to calculate the E-Field between the plates. Then, there is an equation for the force on an electron, based on the E-Field. That (constant) force acts for the whole time the electron is flying between the plates....

    BTW, this question presumably tells you to ignore the fringing field at the entry and exit of the plates...
     
  5. Jan 23, 2009 #4

    berkeman

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    Staff: Mentor

    Re: electron and parallel plate question >:(

    Ack, rl.bhat was too quick for me!
     
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