Question

Medical ultrasound uses a frequency of around 20 MHz to diagnose human conditions and oilments.
a) If the speed of sound in tissue is 1500 m/s, what is the smallest detactable object?
b) If the penetration depth is about 200 wavelengths, how deep can this instrument penetrate?

Answer 1

Dear Student,
$$\begin{gathered} a)detactableobjectwillbecomparabletowavelength \\ so\lambda =\frac{v}{\gamma }=\frac{1500}{20\times {10}^6}=\frac{15}{2}\times {10}^{-5}=7.5\times {10}^{-5}m \\ b)Andpenetrationdepth=200\times 7.5\times {10}^{-5}=15\times {10}^{-3}m \end{gathered}$$
Regard