SPI Exam Review.docx

Sound waves are: a) electric b) mechanical, transverse c) spectral d) longitudinal, mechanical - correct answer D The speed of sound of ultrasound in soft tissue is closest to: a) 1,540 km/sec b) 1.54 km/sec c) 1,500 m/s d) 1,540 mm/sec - correct answer C Which is not an acoustic variable? a) density b) pressure c) distance d) intensity - correct answer D The effects of soft tissue on ultrasound are called: a) acoustic proliferation properties b) dynamic effects c) acoustic propagation properties d) biological effects - correct answer C All of the following are true EXCEPT: a) two waves with identical frequencies must interfere constructively. b) constructive interference is associated with waves that are in-phase. c) out-of-phase waves interfere destructively. d) waves of different frequencies may exhibit both constructive and destructive interference at different times. - correct answer A Put in decreasing order: a) deca b) deci c) micro d) centi - correct answer abdc ______ is the time to complete one cycle a) pulse duration b) pulse period c) period d) duration period - correct answer C Which of the following sound waves is ultrasonic and least useful in diagnostic imaging? a) 30 KHz b) 8 Mhz c) 8,000 Hz d) 3,000 Hz e) 15 Hz - correct answer A ______ is the distance covered by one cycle. a) pulse length b) wavelength c) cycle distance d) cycle duration - correct answer B Which of the following is determined by the source and the medium? a) frequency b) period c) propagation speed d) range resolution - correct answer D Propagation speed = _______ x wavelength a) pulse duration b) period c) # of cycles in the pulse d) frequency - correct answer D As a result of _____ the propagation speed increases. a) increasing stiffness and increasing density b) increasing stiffness and increasing elasticity c) decreasing compressibility and decreasing density d) decreasing stiffness and decreasing density. - correct answer C Put in decreasing order of propagation speed. a) gas b) liquid c) solid - correct answer c b a If the frequency of an ultrasound wave is doubled, what happens to the period? a) doubles b) halved c) remains the same d) 4x greater - correct answer B The units of pulse repetition frequency are: a) per minute b) microseconds c) mm/microseconds d) MHz - correct answer A The time from the beginning of the pulse to the end of that pulse is _______? a) period b) pulse duration c) pulse length d) PRF - correct answer B What happens to the speed of sound in a medium when the bulk modulus increases? a) faster b) slower c) unchanged - correct answer A _________ resolution is determined by the spatial pulse length a) radial b) image c) axial d) angular - correct answer A or C If the wave's amplitude is doubles, what happens to the power? a) nothing b) halved c) doubled d) quadrupled - correct answer D If the level of acoustic variable ranges from 55-105, what is the amplitude? a) 105 b) 50 c) 25 d) 55 - correct answer 25 Power of sound has units of: a) dB b) dB/cm c) watts d) watts/cm^2 - correct answer C If the intensity of a sound beam remains unchanged while the beam area is reduced in half, what has happened to the power? a) quadrupled b) doubled c) halved d) unchanged - correct answer C