Answer #39

The correct answer is C: Amplitude. All of the other parameters are determined by the ultrasound source: period, frequency and wavelength or by the medium: propagation velocity. Period and wavelength are inverses of each other, hence these could have easily been eliminated without much other knowledge since if one was adjustable then naturally the other would have to be also. Propagation velocity is dependent on the medium and can also be eliminated. Finally wavelength is related to propagation velocity and frequency only by the equation c (propagation velocity) = frequency x wavelength, and therefore also can be eliminated. This leaves only amplitude, which is expressed in decibels (dB) and is commonly modified by the ultrasonographer.