## field level

https://doi.org/10.1351/goldbook.F02361
Logarithm of the ratio of two values of a field quantity, usually amplitude. Levels are expressed in different ways: $$L_{F}=\ln (\frac{F}{F_{0}})\ N_{\text{p}}$$, where $$N_{\text{p}}$$ is the symbol for the unit @N04106@ coherent with the SI, or $$L_{F}=20\ \log _{10}(\frac{F}{F_{0}})\ \mathrm{dB}$$, where $$\mathrm{dB}$$ is the symbol for the unit @D01546@.
Source:
Green Book, 2nd ed., p. 79 [Terms] [Book]