(a(i))[2]
By referring to an ultrasound wave, Explain the meaning of specific acoustic impedance.
(a(ii))[2]
An ultrasound wave is incident normally on the interface 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 magnitudes of $Z_1$ and $Z_2$.
(b(i))[1]
State the meaning of attenuation of an ultrasound wave.
(b(ii))[2]
A parallel beam of ultrasound passes through a medium. The incident intensity $I_0$ falls to $0.35I_0$ after travelling through $0.046\ \text{m}$ of the medium. Calculate the linear attenuation coefficient $\mu$ of the ultrasound beam in the medium.