mathematical relation between quantities in a given system of quantities, independent of measurement units
EXAMPLE 1 Q1 = ζ Q2 Q3 where Q1, Q2 and Q3 denote different quantities, and where ζ is a numerical factor.
EXAMPLE 2 T = (1/2) mv2where T is the kinetic energy and v the speed of a specified particle of mass m.
EXAMPLE 3 n = It/F where n is the amount of substance of a univalent component, I is the electric current and t the duration of the electrolysis, and where F is the Faraday constant.