Attenuation of Ultrasound. Ultrasound is absorbed in the body; this complicates the use of ultrasound to image tissues. The intensity of a beam of ultrasound decreases by a factor of 2 after traveling a distance of 40 wavelengths. Each additional travel of 40 wavelengths results in a decrease by another factor of 2. Assume speed of ultrasound in human tissue v = 1540 m/s.
A beam of 2.5 ultrasound begins with an intensity of 2000. After traveling 10 through tissue with no significant reflection, the intensity is about
A physician is making an image with ultrasound of initial intensity 2000 W/m^2. When the frequency is set to 2.5 MHz, the intensity drops to 1000 W/m^2 at a certain depth in the patient's body. What will be the intensity at this depth if the physician changes the frequency to 5.0 MHz?