1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

This is a conceptual question that has to do with SG

  1. Dec 15, 2012 #1
    This is a conceptual question that has to do with SG devices:

    You're given amplitudes for an electron for Sz. What will happen if that same electron is passed through a Z-apparatus? And then one in the x-direction?

    From my understanding the electron then has equal probabilities of spin up & spin down after the Z-apparatus, but the fact that amplitudes were first given in Sz & then were shot through a SG apparatus in the Sz direction confuses me.

    Any insight?
     
  2. jcsd
  3. Dec 15, 2012 #2

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    Re: Stern-Gerlach

    Amplitudes for "up" and "down"? Then you can calculate the probabilities based on those amplitudes. 0.5 for both directions is just a special case.
     
  4. Dec 15, 2012 #3
    Re: Stern-Gerlach

    An electron has an amplitude of 0.8 for Sz = +hbar/2 and
    an amplitude of 0.6 for Sz ==-hbar/2.

    - What is the probability that if we send it into a Stern-Gerlach device with its magnetic field in the z direction, it will emerge in the Sz = +hbar/2 beam?

    -If it does emerge in Sz = +hbar/2 beam,
    and we then send it through a Stern Gerlach machine with its field in the x direction, what is the probability that it will emerge in the Sx = +hbar/2 beam?
    --
    I was under the impression SG devices work like polarizers...
     
  5. Dec 15, 2012 #4

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    Re: Stern-Gerlach

    They work similar to them.

    You can use the Born rule to convert amplitudes to probabilities.
    This is a fancy way to say "square them and take the absolute value".
     
  6. Dec 15, 2012 #5
    Re: Stern-Gerlach

    Is this question really that straight forward? Even though you're given an electron in Sz, and then put it through a magnetic field in the Z-direction, makes no difference? I'm sorry I just thought that the Z-apparatus would only allow either spin up or spin down electrons based on their previous amplitudes.

    Thank you! I need this help!!
     
  7. Dec 15, 2012 #6

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    Re: Stern-Gerlach

    No difference in which way?

    Each electron is either measured as up or down, right.
     
  8. Dec 15, 2012 #7
    Re: Stern-Gerlach


    No, I know each electron can be measured either spin up or spin down, i'm asking what this Z-apparatus does to an electron with this quantum state
     
  9. Dec 15, 2012 #8

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    Re: Stern-Gerlach

    With the Copenhagen interpretation, it will collapse it into either up or down.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: This is a conceptual question that has to do with SG
  1. Conceptual Question (Replies: 4)

  2. Conceptual question (Replies: 3)

Loading...