NIST in 90: Measuring Planck’s Constant

In this 2016 video, NIST physicist Darine Haddad uses a cup of coffee and sugar cubes to explain the significance of Planck’s constant. In 2017, after this video was recorded, NIST measured a new value of the Planck constant with an uncertainty of only 13 parts per billion. This measurement contributed to the final value the revised International System of Units (SI) approved in November 2018.