Question

Please explain your answer

8. An ultrasound pulse was transmitted from the transducer and strikes an interface and returns to the transducer. The transmitted and return time was 39 us. What is the total distance traveled? A. 5 cm. B. 4 cm C. 3 cm. D. 2 cm.

Answer 1

Given the transmitted and return time was 39 mu S. We know there is a 13 mu S rule for ultrasound propagation which states that for every 1 cm of the reflector depth (distance b/w transducer and the interface) the ultrasound pulse takes a time of 13 mu S to get transmitted from the source and return to the source again. The total time of flight for the ultrasound should be 13 miscer second for going and coming back 1 cm of distance between transducer and interface that is total 2 cm of distance. So, if the sound is going and coming back in 39 mu s. which is 3 times 12 mu s that implies the distance b/w the transducer and the interface must be 3 cm and the total distance travelled by the ultrasound should be 6 cm. Therefore So, that's why the answer is none of the above.