Answer:
58.24%
Explanation:
[tex]\rho[/tex] = Density of material
c = Acoustic velocity
Impedance is given by
[tex]Z=\rho c[/tex]
Acoustic impedance of lung
[tex]Z_l=\rho_lc_l=0.18\times 10^6\ kgs/m^2[/tex]
Acoustic impedance of fat
[tex]Z_f=\rho_fc_f=1.34\times 10^6\ kgs/m^2[/tex]
Reflection coefficient is given by
[tex]R=\left(\frac{Z_{l}-Z_{f}}{Z_{l}+Z_{f}} \right)^2\\\Rightarrow R=\left(\frac{0.18\times 10^6-1.34\times 10^6}{0.18\times 10^6+1.34\times 10^6} \right)^2\\\Rightarrow R=0.5824[/tex]
The fraction of incident intensity of a sound pulse will be reflected when sound travels from fat into lung is 58.24%
