(a)[6]
Explain the main principles that underlie the use of ultrasound for obtaining diagnostic information about internal body structures.
(b(i))[2]
Define the specific acoustic impedance.
(b(ii))[2]
The proportion of the incident intensity in an ultrasound beam that is reflected at a boundary between two media depends on the specific acoustic impedances $Z_1$ and $Z_2$ of the media. Discuss qualitatively how the relative sizes of the two specific acoustic impedances affect the reflected intensity.