• Till now, the kilogram is the only one among units of measures pegged to real object.
  • It was pegged to a cylinder (shown in fig) made up of 90% platinum and 10% iridium (In India, salt-shaker-sized cylinder weighing exactly a kilogram in National Physical Laboratory was used as ideal measure of kilogram since 1957.
  • It was serving as reference for variety of industries to keep their weights accurate.
  • But this cylinder’s weight in kilogram is known to fluctuate due to surface contamination with time, making it tricky to define its exact mass.
  • The new measure for kilogram from 2019 will be derived from constants of nature that are all interdependent.
  • ‎It will be set by value of Planck constant in combination with definitions of meter and second.
  • Kibble balance will be used to make accurate measures of Planck constant.
  • Kibble balance is set of scales, which uses force produced by current-carrying wire in magnetic field to balance weight of mass.

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