<prompt> In echocardiography pulses of of ultrasonic waves are admitted at a frequency of1 megahez2 megahez20 Hez2000 Hez  <response>: In echocardiography pulses of ultrasonic waves at a frequency of 2.25 megahez are admitted from a transducer that also functions as a receiver as a receiver to detect waves reflected back from various pas of the hea. Ref:page no 347 Textbook of physiology Volume 1 AK Jain 7th edition 