A copies of the IPK are distributed around the world of which were advice to calibrate the scales and weights throughout every part of the society.
The history of the quest to define units of measurement using constants of nature goes back to the creation of the metric system during the French Revolution. But we will not discuss more of that. The Kibble balance weighs mass against electromagnitic force which was invented in 1975 by British physicist Bryan Kibble, and has been optimized since to reach new levels of accuracy. Despite its complications, the Kibble balance works like a traditional set of scales or beam balance, just like those you might use to weigh groceries. But while these scales usually weigh one mass against another, the Kibble balance weighs mass against an electromagnetic force which can be measured extremely accurately.
The seven units of the metric system and their fundamental constants:
Meter — length. Distance traveled by light in a vacuum in 1/299,792,458 seconds.
Second — time. Exactly 9,192,631,770 cycles of radiation of an atom of caesium-133.
Kilogram — mass. Planck’s constant divided by 6.626,070,15 × 10−34 m−2s.
Mole — amount of substance. Avogadro constant, or 6.022,140,76 ×1023 elementary entities.
Candela — luminous intensity. A light source with monochromatic radiation of frequency frequency 540 × 1012 Hz and radiant intensity of 1/683 watt per steradian.
Kelvin — temperature. Boltzmann constant, or a change in thermal energy of 1.380 649 × 10−23 joules.
Ampere — current. Equal to the flow of 1/1.602 176 634×10−19 elementary charges per second.
More about new this remarkable invention for the better world to measure in the next news.
No comments:
Post a Comment