Question

If a circular ultrasound transducer of radius a = 8 mm operating at a central frequency of 1 MHz has a pressure beam pattern in a medium as given below :
$P(r,0) \propto\sin\frac{ka^2}{4r}$
Here, k is the wave number, r is the axial distance from the center of aperture. The speed of sound in the medium is 1600 ms-1.
The reduction in intensity between r = 8 cm and r = 16 cm is _______ dB. Give your answer as a positive quantity rounded off to two decimal places.

Answer 1

The correct answer is 5.20 to 5.40 (approx)