Time of Flight

Question 1

How long does it take for sound to make a round trip to and from the skin’s surface to a reflector depth of 1 cm in soft tissue?

a. 13 us
b. 150 ms
c. 15 us
d. 2 seconds

Answer 1

a. 13 us

Question 2

In soft tissue, sound travels to a reflector and back to the transducer in 39 us. How deep is the reflector?

a. 2 cm
b. 6 cm
c. 3 cm
d. cannot be determined

Answer 2

c. 3 cm

Question 3

In soft tissue, sound travels to a reflector and back to the transducer in 39 us (39 microseconds or 39 millionths of a second). What is the total distance that the pulse traveled?

a. 2 cm
b. 6 cm
c. 3 cm
d. cannot be determined

Answer 3

b. 6 cm

Question 4

One reflector is 5 times deeper than another. The time of flight of sound to the deeper structure is ____ the time of flight of the shallower reflector.

a. one fifth as much as
b. equal to
c. less than
d. five times more than

Answer 4

d. five times more than