Context: In principle, the Planck constant could be determined by examining the spectrum of a black-body radiator or the kinetic energy of photoelectrons, and this is how its value was first calculated in the early twentieth century. In practice, these are no longer the most accurate methods. The CODATA value quoted here is based on three watt-balance measurements of KJ2RK and one inter-laboratory determination of the molar volume of silicon, but is mostly determined by a 2007 watt-balance measurement made at the U.S. National Institute of Standards and Technology (NIST). Five other measurements by three different methods were initially considered, but not included in the final refinement as they were too imprecise to affect the result.

Question: How was the Planck constant calculated in the early 20th century?
Answer: the Planck constant could be determined by examining the spectrum of a black-body radiator or the kinetic energy of photoelectrons

Question: The value quoted here for the Planck constant is based on a measurement in what year?
Answer: 2007

Question: Where was this measurement made?
Answer: the U.S. National Institute of Standards and Technology (NIST)

Question: What method was was used to obtain the measurement?
Answer: watt-balance measurement

Question: One other measure involved the molar volume of what element?
Answer: silicon

Question: What year was the measurement for the Planck constant value avoided?
Answer: Unanswerable

Question: Where was this measurement disregarded?
Answer: Unanswerable

Question: What could be determined by examining the spectrum of a white-body radiator or the nuclear energy of photoelectrons?
Answer: Unanswerable

Question: What can never be measured with molar volume?
Answer: Unanswerable