Chapter 19-20

Question 1

What is another term for Doppler shift?

Answer 1

Doppler frequency.

Question 2

What occurs when there is relative motion between the sound source and the receiver?

Answer 2

A frequency change

Question 3

What happens when the distance between the sound source and the receiver do not move closer or farther apart?

Answer 3

The frequency remains constant

Question 4

What is the process of extracting the low Doppler frequency from the transducer’s carrier frequency?

Answer 4

Demodulation

Question 5

What is the equation for a Doppler shift

Answer 5

Doppler shift = reflected frequency - transmitted frequency

Question 6

What happens when transmitted sound waves strike red blood cells that are moving through the body?

Answer 6

A Doppler shift

Question 7

When blood moves toward the transducer, is the Doppler shift positive or negative? Does this mean the reflected frequency is higher or lower than the transmitted?

Answer 7

The Doppler shift is positive when blood moves toward the transducer. This means that the reflected frequency is higher than the transmitted frequency.

Question 8

When blood moves away from the transducer, is the Doppler shift positive or negative? Does this mean the reflected frequency is higher or lower than the transmitted?

Answer 8

The Doppler shift is negative when blood moves away from the transducer. This means that the reflected frequency is lower than the transmitted frequency.

Question 9

Do Doppler frequencies indicate velocity, speed, or both? Why?

Answer 9

Velocity. Speed is a magnitude meaning it is distance/time whereas velocity has a magnitude and direction so its distance/time in a specific direction.

Question 10

What is the relationship between the velocity of blood and a Doppler shift

Answer 10

They are directly related. Faster velocities have greater frequency.