Acoustics/formulas/Max efficiency

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{{:Acoustics/formulas/Max efficiency}}

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${\eta }_{\max }=1-\frac{2}{k_{\mathrm{e}\mathrm{f}\mathrm{f}}\sqrt{Q_E{Q}_{m0}}}(k_{\mathrm{e}\mathrm{f}\mathrm{f}}\sqrt{Q_E{Q}_{m0}}\ll 1)$