(a)[2]
Suggest why the ultrasound produced by the transducer is pulsed.
(b(i))[2]
State what is meant by specific acoustic impedance.
(b(ii))[2]
A parallel ultrasound beam of intensity $I_0$ is incident normally on the boundary between two media, as shown in Fig. 5.1. The media have specific acoustic impedances $Z_1$ and $Z_2$. The intensity of the ultrasound beam transmitted across the boundary is $I_T$. Explain the effect of the values of $Z_1$ and $Z_2$ on the ratio $I_T / I_0$.