Question

A medical ultrasound imaging system sends out a steady stream of very short pulses. To simplify analysis, the reflection of one pulse should be received before the next is transmitted.
If the system is being used to create an image of tissue 15 cm below the skin, what is the minimum time between pulses?

Also how many pulses per second does this correspond to?

Answer 1

Answer:

Minimum time = 1.95x10^-4 s

Number of pulses = 5128.21 pulses/s

Explanation:

We have the speed of sound waves through human tissue with a value of 1540 m/s, to calculate the time it takes for the pulse to travel a distance of 30 cm (since the pulse will first travel a distance of 15 cm and then it will return another 15 cm to be detected by the equipment), therefore, the time between the two pulses will be equal to:

tminimum = 0.30 m/1540 m/s = 1.95x10^-4 s

To calculate the number of pulses, one second must be divided over the minimum time between the two pulses, as follows:

npulses = 1 s/1.95x10^-4 s = 5128.21 pulses/s