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!

Motion of a hydrogens ions

  1. Dec 16, 2008 #1
    1. The problem statement, all variables and given/known data
    Some hydrogens and deuterium ions are accelerated by a potential difference V. These ions entered then in a region with a magnetic field B orthogonal to their velocity. In the position H and K (along the axis parallel to the velocity) there are two sensors and the distance between them is d. Find the the V you need to make the hydrogen ions go towards H and deuterium towards K


    2. Relevant data
    d=0.8cm
    B=0.4T
    q(e)=1.6*10(-19)
    m(H)=1.67*10^-27
    m(D)=3.34*10^-21Kg


    3. The attempt at a solution
    Velocity of the ions after the acceleration by a potential difference V:
    qV(1)=1/2mv^2+qV(2) ==> v=sqrt[(2qV)/(m)] where m is m(D) or m(H)

    motion of the ions in the magnetic field: circular motion with radius:
    r(D)=v(D)m(D)/qB
    r(H)=v(H)m(H)/qB

    The distance between the two sensors is d, so r(D)-r(H)=d ==> 4qV=dqB ==> V=0,00008V

    Is this right?
     
  2. jcsd
  3. Dec 16, 2008 #2

    Redbelly98

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Without seeing a figure of the magnetic field region, we can't say.

    By any chance are the ion trajectories 90 degrees, or 1/4, of a full circle?
     
  4. Dec 16, 2008 #3
    It's 1/2 circle
     

    Attached Files:

    • B.jpeg
      B.jpeg
      File size:
      30.9 KB
      Views:
      50
  5. Dec 16, 2008 #4

    Redbelly98

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Okay, that makes more sense now.

    The distance between H and K is not the difference in radii of the two circles. Can you look at the figure again and see how that distance does relate to the circles?
     
  6. Dec 16, 2008 #5
    Is it the difference between the diameters?
     
  7. Dec 16, 2008 #6

    Redbelly98

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

  8. Dec 18, 2008 #7
    Now it works... thanks!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Motion of a hydrogens ions
  1. Hydrogen atom (Replies: 1)

Loading...