The ultrasonic sound waves employed in ultrasound machine for medical sonography have the frequency of

Frequency refers to a characteristic of the sound that is, the number of times that conduction paicles vibrate back and foh per second. Frequency of sound waves is usually between 1 and 20 MHz in medical sonography. Hence the best answer for this question would be A. 2-20 MHz Christensen's Physics of Diagnostic Radiology, 4/E,Pg no 347