# Rayl

Physical unit
Unit name Rayl
Unit symbol ${\ displaystyle \ mathrm {Rayl}}$ , ${\ displaystyle \ mathrm {rayl}}$ Physical quantity (s) Acoustic impedance
Formula symbol ${\ displaystyle Z _ {\ mathrm {F}}}$ dimension ${\ displaystyle {\ mathsf {M \; L ^ {2} \; T ^ {- 1}}}}$ system CGS system of units
In SI units ${\ displaystyle \ mathrm {1 \, MKS ~ Rayl = 1 \; {\ frac {N \, s} {m ^ {3}}}}}$ In CGS units ${\ displaystyle \ mathrm {1 \, CGS ~ Rayl = 1 \; {\ frac {g} {cm ^ {2} \, s}}}}$ Named after Lord Rayleigh
Derived from Centimeter , gram , second

The Rayl (named after the English physicist John William Strutt, 3rd Baron Rayleigh ) is an outdated and illegal unit of the specific acoustic impedance . There are two different definitions that differ by an order of magnitude:

1. In the CGS system of units :
${\ displaystyle 1 \ \ mathrm {CGS ~ Rayl} = 10 \ {\ mathrm {kg} \ over \ mathrm {m ^ {2} \ s}} = 1 \ {\ mathrm {g} \ over \ mathrm {cm ^ {2} \ s}} = 10 \ {\ mathrm {Pa \ s} \ over \ mathrm {m}}}$ 2. In the MKS unit system :
${\ displaystyle 1 \ \ mathrm {MKS ~ Rayl} = 1 \ {\ mathrm {kg} \ over \ mathrm {m ^ {2} \ s}} = 0 {,} 1 \ {\ mathrm {g} \ over \ mathrm {cm ^ {2} \ s}} = 1 \ {\ mathrm {Pa \ s} \ over \ mathrm {m}}}$ ## Individual evidence

1. Holger Pettersson, Gustav Konrad von Schulthess, David J. Allison: The Encyclopaedia of Medical Imaging: Physics, techniques and procedures / volume editors, Gustav K. von Schulthess, Hans-Jørgen Smith . Informa Health Care, 1998, ISBN 82-91942-01-3 .
2. ^ François Cardarelli: Encyclopaedia of scientific units, weights, and measures . Springer, 2003, ISBN 1-85233-682-X , pp. 555 ( limited preview in Google Book search).
3. Often referred to as the original definition.
4. ^ Z. Maekawa, Peter Lord: Environmental and architectural acoustics . Taylor & Francis, 1994, ISBN 0-419-15980-0 , pp. 366 .