Question

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 1.7kms^-1? The operating frequency of the scanner is 4.2MHz.

Answer 1

λ = ? u = 1.7kms^-1 = 1700ms^-1

v = 4.2 × 10⁶ Hz, u = vλ = or λ = \(\frac{u}{v}\)

or λ =\(\frac{1700}{4.2×10^6}\)  m = 4.05 × 10^-4 m = 0.405mm.