(a(i))[2]
Using an ultrasound wave, explain what specific acoustic impedance means.
(a(ii))[2]
An ultrasound wave is incident normally on the boundary between two media. The media have specific acoustic impedances $Z_1$ and $Z_2$. State how the ratio $\frac{\text{intensity of ultrasound reflected from boundary}}{\text{intensity of ultrasound incident on boundary}}$ varies with the relative sizes of $Z_1$ and $Z_2$.
(b(i))[1]
State the meaning of attenuation for an ultrasound wave.
(b(ii))[2]
A parallel beam of ultrasound travels through a medium. The incident intensity $I_0$ falls to $0.35 I_0$ after passing through $0.046\,\text{m}$ of the medium. Calculate the linear attenuation coefficient $\mu$ of the ultrasound beam in the medium.