17.7 Ultrasound

Why is it possible to use ultrasound both to observe a fetus in the womb and also to destroy cancerous tumors in the body?

Unless otherwise indicated, for problems in this section, assume that the speed of sound through human tissues is 1540 m/s.

What is the sound intensity level in decibels of ultrasound of intensity $\text{10}^{5} \text{W}/\text{m}^{2}$, used to pulverize tissue during surgery?

Unless otherwise indicated, for problems in this section, assume that the speed of sound through human tissues is 1540 m/s.

Find the sound intensity level in decibels of $2.00 \times \text{10}^{–2} \text{W}/\text{m}^{2}$ultrasound used in medical diagnostics.

Unless otherwise indicated, for problems in this section, assume that the speed of sound through human tissues is 1540 m/s.

In the clinical use of ultrasound, transducers are always coupled to the skin by a thin layer of gel or oil, replacing the air that would otherwise exist between the transducer and the skin. (a) Using the values of acoustic impedance given in the table calculate the intens…

Unless otherwise indicated, for problems in this section, assume that the speed of sound through human tissues is 1540 m/s.

(a) Find the size of the smallest detail observable in human tissue with 20.0-MHz ultrasound. (b) Is its effective penetration depth great enough to examine the entire eye (about 3.00 cm is needed)? (c) What is the wavelength of such ultrasound in $0ºC$ air?

Unless otherwise indicated, for problems in this section, assume that the speed of sound through human tissues is 1540 m/s.

(a) How far apart are two layers of tissue that produce echoes having round-trip times (used to measure distances) that differ by $0.750 μs$ ? (b) What minimum frequency must the ultrasound have to see detail this small?

Unless otherwise indicated, for problems in this section, assume that the speed of sound through human tissues is 1540 m/s.

A dolphin is able to tell in the dark that the ultrasound echoes received from two sharks come from two different objects only if the sharks are separated by 3.50 m, one being that much farther away than the other. (a) If the ultrasound has a frequency of 100 kHz, show this…

Unless otherwise indicated, for problems in this section, assume that the speed of sound through human tissues is 1540 m/s.

Ultrasound reflected from an oncoming bloodstream that is moving at 30.0 cm/s is mixed with the original frequency of 2.50 MHz to produce beats. What is the beat frequency? (Assume that the frequency of 2.50 MHz is accurate to seven significant figures.)