h: the Planck constant
November 29, 2024•97 words
• The Planck constant is one of the fundamental constants of quantum
mechanics. Quantum mechanics shows us that energy is exchanged
and absorbed in specific amounts, known as “quanta.” h defines the
size of those quanta, which can be visualized as packets of energy
exchanged by matter.
• In the revised SI, the Planck constant h is equal to exactly
6.626 070
15 × 10-34
Joule seconds.
This value for the Planck constant was only
finalized in 2017, and that value is key to redefining the kilogram.
• h helps to define the kilogram, kelvin and candela.