Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The unit - a.u

  1. Jan 14, 2009 #1
    Does anyone knows what this unit "a.u" means? I found it on many graphs, where "a.u" represents the unit of |E|^2 (E represents electromagnetic field). How do I convert "a.u" to SI unit?
     
  2. jcsd
  3. Jan 14, 2009 #2

    Hootenanny

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Are you sure that you have that right? a.u. usually refers to the Astronomical Unit, which is a measure of distance (I can't remember the exact conversion factor, but I'm sure its of the order of 109m).
     
  4. Jan 14, 2009 #3

    jtbell

    User Avatar

    Staff: Mentor

    I suspect it means "arbitrary unit", that is, no particular unit at all. In this case those graphs are intended to show only the relative values of E^2 at different points on the graph, without regard for the overall scale.
     
  5. Jan 14, 2009 #4

    Hootenanny

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Well I never knew that! You learn something new every day, thanks jtbell.
     
  6. Jan 14, 2009 #5

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    In many journals, such as the Phys. Rev. journals, they no longer permit the use of "a.u." abbreviation. They want those figures to at least say "arb. units" or even "arbitrary units", to avoid the confusion with Astronomical Unit.

    Zz.
     
  7. Jan 14, 2009 #6
    I see. That makes sense now, thank you very much.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: The unit - a.u
  1. Unit Of Resistivity (Replies: 3)

  2. Si units (Replies: 1)

  3. Understanding units (Replies: 15)

  4. Units of wavenumber (Replies: 2)

  5. The Unit H (Replies: 5)

Loading...