Answer #15

The correct answer is A: As the wavelength increases the frequency decreases in a particular medium. Frequency and wavelength are inversely proportional to each other as seen in the equation: propagation velocity = frequency * wavelength.

Propagation velocity is determined by the medium only. For soft tissues we use a value of 1540 meters/second. So as the frequency increases for a given medium, the velocity will not change but rather the wavelength will decrease. Hence choice B is incorrect. For a given frequency bone will have a longer wavelength than soft tissue since the propagation velocity in bone is higher at around 4000 meters/sec. Soft tissue has a lower velocity of 1540 m/s and wavelength is directly proportional to propagation velocity. Hence choice C is incorrect. Finally as we seen in the bone vs soft tissue example, as the stiffness increases for an object the propagation velocity increases causing the wavelength to increase. Hence choice D is incorrect.