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Homework Help: Uncertainty principle and tv picture tube

  1. Mar 10, 2005 #1
    hey, Im really confused with this problem, i have tried to solve it for a while now but i cant seem to get it, i really dont even know where to start with it.

    In a TV picture tube the accelerating voltage is V, and the electron beam passes through an aperture with a diameter of Delta_y and hits a screen which is a distance of x away.

    What is the uncertainty in position of the point where the electrons strike the screen?
    Use h for Planck's constant, m_e for the mass of an electron, and e for the magnitude of the charge on an electron.

    any help would be great.
  2. jcsd
  3. Mar 11, 2005 #2


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    The idea is that the uncertainty in the position of the particle after it passes the aperture is [itex]\Delta y[/itex], which, if it is small enough, leads to an uncertainty in the momentum of the particle.

    Use Heisenberg to find the order of this uncertainty in momentum.
  4. Mar 11, 2005 #3
    when i find the uncertainty in the momentum that will be the x component of the momentum since it is a distance x away from the tv?
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