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Suppose i am performing the diffraction experiment using a single electron

  1. Aug 14, 2012 #1
    i was going through the diffraction experiment and had a question that i would like to ask:

    suppose i am performing the diffraction experiment using a single electron,firstly how the energy contained in electron in terms of its physical properties such as charge,angular momentum and spin can be seen in waves?.
    second, if i put an apparatus to look for the electron how is the energy of wave transforming back into the particle and then seen in nature of particle such as spin, angular momentum and charge?

    or if someone could tell me that how is the feild energy of particle is transformin into the energy of wave. it appears as if there is a violation to conservation of energy.
    Last edited: Aug 14, 2012
  2. jcsd
  3. Aug 14, 2012 #2

    Simon Bridge

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    Re: collapse

    It isn't. An electron is a particle ;)
    It is the position (and, therefore, momentum) wavefunction that has the wave properties.

    The deBroglie "matter waves" are a stepping-stone concept to help you get used to this.
    Basically, matter and energy are the same thing - energy has a frequency - therefore matter has a frequency - therefore we expect to see wave-like behavior from matter.
    for eg. [itex]E=mc^2=h\nu[/itex] relates the wave and material properties. However - the actual wave is statistical rather than physical - it's just called that because the math is similar to the math for physical waves.

    (note: when we talk about the energy of an electron we usually mean it's kinetic energy or the combination of rest-mass and kinetic energy. Energy due to, say, charge would be electromagnetic potential energy.)
    It isn't - the electron was always a particle.

    In wave mechanics, the electron source and the slits "prepare the initial state" of the electron ... the slits act to measure the position of the electron, establishing the position wave-function. The narrower and fewer the slits the more certain the position, which makes the momentum very uncertain ... and it is the momentum that exhibits interference.

    This interference determines the probability of detecting an electron at some place.

    See: http://arxiv.org/pdf/quant-ph/0703126]
    ... the notation can be a bit scary if you are not used to it, just take it slow.
    Last edited: Aug 14, 2012
  4. Aug 16, 2012 #3
    Re: collapse

    So what will you say about the diffraction pattern. The electron should not give a continuous distribution of energy along the screen at same time.
  5. Aug 16, 2012 #4

    Simon Bridge

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    Re: collapse

    It's pretty :)
    The electron does not give a continuous energy along the screen at the same time.
    Each electron's energy arrives at a particular spot on the screen in one go.

    The interference and diffraction come from the statistical behavior.
    I believe I covered this in the rest of my previous reply.

    You are thinking of the classical models for particles and waves.
  6. Aug 16, 2012 #5
    Re: collapse

    i get it
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