Ultrasound Physics and Instrumentation, 5e Chapter 7: Level 1 Quiz Answers. 1) Which of the following is stated in the introduction of the chapter?

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1 Ultrasound Physics and Instrumentation, 5e Chapter 7: Level 1 Quiz Answers 1) Which of the following is stated in the introduction of the chapter? a) Because of the importance of Doppler, this chapter is a comprehensive in its treatment of hemodynamic measurement. b) This chapter is part of a trilogy, including chapters 12 and 13. c) Doppler is a relatively new technique, especially as applied to ultrasound d) Doppler represents a very narrow category whose understanding is dependent on understanding the basic principles such as sound, waves, and transducers. Answer: B (pp Introduction) 2) The Doppler Effect is an apparent change in frequency because of a change in amplitude due to relative movement between a source and an observer. Answer: False (change in wavelength not amplitude) (pp ) 3) A shorter wavelength represents a higher frequency and occurs when relative motion is toward an observer. Answer: True (pp ) 4) When the motion is away from the observer, the returning frequency is lower than the transmitted frequency. Answer: True (pp ) 5) If there is an observer and there is a stationary train, it is not possible to have a Doppler shift. Answer: False (if the observer moves relative to the train, a Doppler shift would result (shift is caused by relative motion). (pp )

2 6) The fact that a faster moving train would cause a greater Doppler shift indicates that: a) the Doppler shift is directly related to the velocity. b) the Doppler shift is directly related to the wavelength. c) the Doppler shift is inversely related to distance. d) the Doppler shift is inversely related to the amplitude. e) the Doppler shift is the reason why trains can move. Answer: A (pp ) 7) Since the Doppler Effect is caused by motion, movement by either the source or the results in a Doppler frequency shift. Answer: Relative, observer (pp ) 8) Which famous physicist was mentioned when discussing basic Doppler theory? a) Kepler b) Newton c) Curie d) Einstein e) More than one Answer: D (pp ) 9) If the transmitted frequency is 2.0 MHz and an observer hears a signal at MHz, the Doppler shift is: a) 3 khz b) MHz c) + 3 khz d) MHz e) MHz Answer C (2.003 MHz MHz = MHz = 3 khz) (pp ) 10) Write the wavelength equation. Answer: λ c f (pp )

3 11) The pictures that were used in this chapter to show the relationship between the operating frequency and the wavelength and between the propagation velocity and the wavelength: a) showed wavefronts and a clock b) showed transverse waves and a clock c) showed wavefronts and a ruler d) showed transverse waves and a ruler Answer: C (pp 227 & 228) 12) Regarding the simplified numeric form of the Doppler equation, the author stated: a) this simplified form was included since it is the easiest method for recall. b) this simplified form was included as it yields the most intuitive understanding of the equation. c) he prefers that students learn this form as it allows for any angle (not just directly towards or away from the observer). d) does not like this equation because it is too simple. e) is not a proponent of learning the equation in this form as it leads to rote memorization and it hides relationships. Answer: E (pp ) 13) For a given interrogating frequency, if the velocity triples, what happens to the Doppler shift frequency? Answer: The Doppler shift triples since the Doppler frequency is proportional to the operating frequency. (pp ) 14) The picture that was used to show the angle effect on the Doppler shift included: a) a car and two people. b) a car and two ears. c) a train and two people. d) a train and two ears. e) an ambulance and two dogs. f) two dogs and one fire hydrant. Answer: D (pp )

4 15) In the completed form of the Doppler equation: a) the cosine is in the numerator. b) the sine is in the numerator. c) the cosine is in the denominator. d) the sine is in the denominator. Answer: A (pp ) 16) Describe the Rayleigh scattering/frequency paradox: Answer: Although scattering increases with increasing frequency (making it appear as if stronger Doppler would be achieved with higher operating frequency), stronger Doppler signals are generally achieved using lower operating frequencies. (pp ) 17) What word refers to the aggregate form of red blood cells responsible for the appearance of spontaneous contrast? a) clotus b) erythrocytitis c) hemoglobulus d) rouleau e) hemoagrarian Answer: D (pp ) 18) What is the best estimate of the Doppler angle in the associated figure? a) 0 degrees b) 30 degrees c) 90 degrees d) 180 degrees e) Cannot be determined Answer: D (pp )

5 19) What is represented by the associated symbol? a) The sum of Doppler shifts b) The multiplication Doppler shifts c) The division of Doppler shifts d) The integration of Doppler shifts e) The Fourier transform of Doppler shifts Answer: A (pp ) 20) When discussing clutter signals and wall filtering, the book stresses that: a) you need to make sure that you rarely use wall filters. b) you need to pay attention to the difference between amplitude and frequency. c) the frequency shift is related to the Doppler signal strength. d) clutter signals are usually low amplitude. e) Doppler does not require much dynamic range. Answer: B (pp ) Bonus question: List the data displayed on the three axes of the Doppler display. Horizontal: Vertical: Imaginary: Answer: (pp ) Horizontal: Vertical: Imaginary: time frequency (or) velocity signal amplitude