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

Picture of the 2 lines on a platinum iridium bar

  1. Mar 2, 2012 #1
    Hello all,

    The standard meter was said to be the distance between two scratches on a platinum iridium bar.


    Where are these scratches? I only see the bar.
  2. jcsd
  3. Mar 2, 2012 #2


    User Avatar

    Staff: Mentor

    There doesn't appear to be a good picture on wikipedia. Perhaps some google searching would turn up something else?
  4. Mar 2, 2012 #3


    User Avatar
    Science Advisor
    Gold Member

    I must say, I never thought of that before but those scratches will need to be VERY FINE for the standard length to be precise. You can probably only see them with a lens.
    When they are used for making or calibrating a sub standard, they 'know' pretty well where to look for these tiny scratches because they already have a 'crude' 1m measure. They can't 'lose them'.
  5. Mar 2, 2012 #4


    User Avatar
    Science Advisor
    Homework Helper

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Picture of the 2 lines on a platinum iridium bar
  1. Copper Iridium Metal (Replies: 17)

  2. Force on 2 power lines (Replies: 13)

  3. Bar magnet. (Replies: 9)