Mole (unit) and growth chamber lighting for plants is sometimes expressed in micromoles per square meter per second, where 1 mol photons = photons. In 2011, the 24th meeting of the General Conference on Weights and Measures (CGPM) agreed to a plan for a possible revision of the SI base unit definitions at an undetermined date. The 26th meeting of the CGPM, in a formal vote on 16 November 2018, approved the proposed redefinition of SI base units mole, kilogram, ampere and kelvin. One mole of a substance will have exactly specified "elementary entities" of that substance. The definition of the mole
Units of energy Units of energy Because energy is defined via work, the SI unit for energy is the same as the unit of work – the joule (J), named in honor of James Prescott Joule and his experiments on the mechanical equivalent of heat. In slightly more fundamental terms, 1 joule is equal to 1 newton metre and, in terms of SI base units An energy unit that is used in atomic physics, particle physics and high energy physics is the electronvolt (eV). One eV is equivalent to 1.60217653×10 J. In spectroscopy the unit cm = 0.000123986 eV is used to represent