Mynd:Platinum-Iridium meter bar.jpg

Frá Wikipedia, hin frælsa alfrøðin

No higher resolution available.

Platinum-Iridium_meter_bar.jpg (270 × 175 pixel, file size: 21 KB, MIME type: image/jpeg)

This file is a shared upload and may be used by other projects.

International Prototype Metre standard bar made of platinum-iridium. This was the standard until 1960, when the new SI system used a krypton-spectrum measurement as the base. In 1983 the current metre was defined by a relationship to the speed of light in a vaccuum. (NIST)

http://www.mel.nist.gov/div821/webdocs-14/lsi_2.htm

Public domain This image is in the public domain because it contains materials that originally came from the National Institute of Standards and Technology.

Hesar síður slóða til hesa mynd: