Consider a gas with molar mass M. If the sound at frequency f is introduced to a tube of this gas temperature T then an internal acoustic standing wave is set up with nodes separated by L. The adiabatic constant (γ = Cp/Cv) is
1
\(\frac{{M\,{f^2}{L^2}}}{{RT}}\)
2
\(\frac{{M\,{f^2}{L^2}}}{{4RT}}\)
3
\(\frac{{4M\,{f^2}{L^2}}}{{RT}}\)
4
\(\frac{{3M\,{f^2}{L^2}}}{{2RT}}\)