15.7 A hospital uses an ultrasonic scanner to locate tumours in a tissue. What is the wavelength of sound in the tissue in which the speed of sound is 1.7 km/s? The operating frequency of the scanner is 4.2 MHz.


Speed of sound in the tissue, v = 1.7 km/s = 1.7×103 m/s
 Operating frequency of the scanner, ν = 4.2 MHz = 4.2×106 Hz
 The wavelength of sound in the tissue:
λ=vν=1.7×1034.2×106=4.1×10-4m