Question

An ultrasound pulse was transmitted from the transducer and strikes an interface and returns to the transducer. The transmitted and return time was 39 ?s. What is the total distance traveled?

A. 5 cm.

B. 4 cm.

C. 3 cm.

D. 2 cm.

Answer 1

The answer to the problem is none of the above .

We know there is a 13 micro second rule for ultrasound propogation which states that for every 1cm of the reflector depth (distance between transducer and the interface) the ultrasound pulse takes a time of 13 microsecond to get transmitted from the source and return to the source again.

The total time of flight for the ultrasound should be 13 microsecond for going and coming back 1 cm of distance between tramsducer and interface that is total 2 cm of distance.

So if the sound is going and coming back in 39 microsecond which is 3 times 13 microsecond that implies that the distance between the transducer and the interface must be 3 cm and the total distance travelled by the ultrasound should be 6 cm.

So that's why the answer is none of the above.