Machine-translated by Google. Questions are authored in English.
Top

Discussion

A primary standard of a quantity is one that

  • A.is used for the everyday calibration of workshop instruments
  • B.is kept in a laboratory and calibrated against a working standard
  • C.is carried between laboratories for comparison purposes
  • D.realises the unit from its definition

Answer: D

Correct answer: realises the unit from its definition

A primary standard embodies the unit directly, by an experiment traceable to the definition rather than by comparison with anything else - a Josephson array for the volt, a quantum Hall device for the ohm. It is held at a national laboratory and is not used for routine work.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.