The Doppler shift of ultrasonic waves can measure the speed of blood in an artery.If the frequency of the stationary source is 100 kHz and the reflected sound has a Doppler shift of 300 Hz,what is the blood flow speed? (The speed of sound inside the body is 1500 m/s. )
A) 1.0 m/s
B) 1.5 m/s
C) 2.2 m/s
D) 3.3 m/s

Question

Quizplus · Accepted Answer

The Doppler shift of sound wave can be expressed as:
Doppler shift = (2 * speed of blood * frequency of ultrasonic wave) / speed of sound inside the body
We can rearrange the formula to solve for the speed of blood:
Speed of blood = (Doppler shift * speed of sound inside the body) / (2 * frequency of ultrasonic wave)
Plugging in the given values, we get:
Speed of blood = (300 Hz * 1500 m/s) / (2 * 100 kHz) ≈ 2.25 m/s
Rounding off to the nearest tenth, we get 2.2 m/s as the blood flow speed, which is closest to option C.

The Doppler Shift of Ultrasonic Waves Can Measure the Speed