# A Doppler blood flow meter emits ultrasound at a frequency of 5.0 MHz. What is the beat frequency between the emitted waves and the waves reflected from blood cells moving away from the emitter at 0.15m/s? Assume that v_sound=1540m/s in blood.

## The Doppler shift, delta f, of the blood cells moving away is 2 V/v_sound * 5.0 *10^6 Hz.

V = 0.15 m/s = the blood cell speed and v_sound = 1540 m/s.

The factor of 2 is there because the frequency is shifted twice (when received and when sent back).

delta f = 2*5*10^6*0.15/1540 = 974 Hz

The beat frequency (of the transmitted beam combined with the reflected beam)equals delta f

## thank you Drwls

## thank you

## perfect answer...thank you so much

## To find the beat frequency between the emitted waves and the waves reflected from blood cells, we need to use the Doppler effect equation:

Î”f = (2 * v_r * f) / c

where:

Î”f is the change in frequency (beat frequency)

v_r is the velocity of the blood cells moving away from the emitter

f is the frequency of the emitted ultrasound waves

c is the speed of sound in the medium (blood in this case)

Given:

f = 5.0 MHz = 5.0 * 10^6 Hz

v_r = 0.15 m/s

c = 1540 m/s

Substituting the given values into the equation, we have:

Î”f = (2 * 0.15 * 5.0 * 10^6) / 1540

Now, let's calculate the beat frequency.