He developed mathematical formulae to describe phenomena such as the relation between the refraction of light and the density of a pure transparent substance, and the relation between a metal's electrical and thermal conductivity and temperature (Wiedemann–Franz–Lorenz law).

Lorenz was born in Helsingør and studied at the Technical University in Copenhagen.

The formula for the mathematical relationship between the refractive index and the density of a medium was published by Lorenz in 1869 and by Hendrik Lorentz (who discovered it independently) in 1878 and is therefore called the Lorentz–Lorenz equation.

Additionally, Lorenz laid the foundations for ellipsometry by using Fresnel's theory of refraction to discover that light reflected by a thin transition layer between two media becomes elliptically polarized.

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