Physics Questions

48 Questions  I  By Paga
QUESTIONS

Changes are done, please start the quiz.

 1 The frequency closest to the lower limit of US is
 A. 19,000 kHz
 B. 10,000 MHz
 C. 20,000 msec
 D. 15,000 Hz
 2 Put in decreasing order
 A. Deca, deci, centi, micro
 B. Deci, deca, centi, micro
 C. Micro, centi, deca, deci
 D. Centi, micro, deci, deca
 3 Which of the following is determined by the source and the medium?
 A. Frequency
 B. Period
 C. Propagation speed
 D. Range resolution
 4 As a result of _____________ the propagation sped 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
 5 Put in decreasing order of propagation speed.
 A. Gas, liquid and solid
 B. Solid liquid and gas
 C. Liquid gas solid
 6 If the frequency of US is increased from 0.77 MHz to 1.54 MHz, what happends to the wavelength?
 A. Doubles
 B. Halved
 C. Remain the same
 D. 4 times greater
 7 If the intensity of a sound beam remains unchanged while the beam area is reduced in half, what has happend to the power?
 B. Doubled
 C. Halved
 D. Unchanged
 8 What is the minimum value of the duty factor?
 A. 10
 B. 1%
 C. 1
 D. 0.0%
 9 If a 5MHz sound wave is traveling in the tissues listed below, which will have the longest wavelength?
 A. Fat
 B. Air
 C. Muscle
 D. Bone
 10 As the impedances (z (rayls) = density (kg/m^3) x prop. speed (m/s) or acoustic resistance to sound traveling in a medium, becomes vastly different, the
 A. Reflection increases
 B. Transmission increases
 C. Refraction increases
 D. Absorption increases
 11 With normal incidence, what factors affect refraction of US?
 A. Propagation speeds
 B. Frequencies
 C. Attenuation coefficients
 D. None of the above
 12 The most likely amount of reflection at a boundary between soft tissue is:
 A. 1%
 B. 22%
 C. 34%
 D. 99%
 13 How many cm are 60 millimeters
 A. 600
 B. 6
 C. 0.6
 D. 0.006
 14 How is range ambiguity artifact eliminated?
 A. Lower the PRF
 B. Raise the PRF
 C. Increase the gain
 D. Use a lower frequency transducer
 15 Under which of the following conditions is lateral resolution improved?
 A. Decreased beam diameter
 B. Decreased pulse duration
 C. Decreased imaging depth
 D. Decreased pixel size
 E. Decreased spatial pulse length
 16 Which transducer would be best to image superficial structures?
 A. Small diameter, high frequency
 B. Small diameter, low frequency
 C. Large diameter, high frequency
 D. Large diameter, low frequency
 17 If the frame rate increases and the lines per frame is unchanged, what else must happen?
 A. US speed increases
 B. Frequency increases
 C. Depth increases
 D. Depth decreases
 18 TRUE OR FALSEA system which was working well now does not display clear images in the far field.  This may be a problem with the monitor.
 A. True
 B. False
 19 If the output of an US machine is calibrated in dB and the output is increased by 20 dB, the beam intensity is increased
 A. 100 times
 B. 1,000,000 times
 C. 20 times
 D. 10 times
 20 Which of the following will result in the greatest number of shades of grapy in a digital image display?
 A. Large pixels with many bits/pixel
 B. Small pixels with few bits/pixel
 C. Many TV lines per frame
 D. High contrast
 E. Narrow dynamic range
 21 With good images on the CRT but not on the strip chart recorder, one should
 A. Increase the gain
 C. Check the same converter
 22 Compression is used to
 A. Decrease the amplitude
 B. Decrease the range of amplitudes
 C. Decrease the range of frequencies
 23 In which of these biologic tissues will sound waves propagate most quickly?
 A. Tendon
 B. Blood
 C. Lung
 D. Fat
 E. Amniotic fluid
 24 All of the following statements regarding in-vitro bioeffects are true EXCEPT?
 A. In vitro bioeffects conclusions are clinically relevant
 B. In vitro bioeffects are always real
 C. In vitro bioeffects are vey important
 D. In vitro bioeffects may not be applicable to clinical settings
 25 Which of the following improves signal to noise ratio
 A. Dynamic range
 B. Frame averaging
 C. Gray scale
 D. Edge enhancement
 26 Under which circumstances is cavitation most likely to occur
 A. High frequency and low power
 B. High intensity and high frequency
 C. Low intensity and low frequency
 D. Low frequency and high signal amplitude
 27 What is displayed on the y-axis of an m-mode image?
 A. Time
 B. Time of flight
 C. Echo intensity
 D. Red blood cell velocity
 28 An amplifier of an ultrasound system increases the voltage of a signal from 0.0001 to 0.1 volt.  What is the amplification
 A. 60 dB
 B. 30 dB
 C. 1,000 dB
 D. 90 dB
 29 The impedances of tissue is 3 x 10^5 rayls and for the PZT crystal is 6 x 10^6 rayls.  What is the best impedance for the matching layer?
 A. 36 x 10^5
 B. 3,600
 C. 10,000
 D. 9.5 x 10 ^5
 E. 9 x 10^4
 30 Put in increasing order of propagation speed
 A. Air water bone
 B. Water air bone
 C. Bone air water
 D. Air bone water
 E. Bone water air
 31 What is propagation speed determined by
 A. Wavelength
 B. Intensity and density
 C. Amplitude
 D. Density and elasticity
 E. Density and amplitude
 32 If 300,000 cycles occur in a second, what is the wave's frequency?
 A. 3 MHz
 B. 30 kHz
 C. 300 MHz
 D. 3 kHz
 E. 0.3 MHz
 33 All of the following will improve temporal resolution EXCEPT
 A. Increased line density
 B. Single rather than multi focus
 C. Higher frame rate
 D. Shallower depth of view
 E. Slower speed of sound in a medium
 34 What component of a transducer changes electrical to mechanical and mechanical back to electrical engergy?
 A. PZT
 B. Transducer
 35 What are typical clinical Doppler frequencies
 A. 1 - 10,000 Hz
 B. 1 - 10 MHz
 C. 2 - 1,000 kHz
 D. 40 - 45 kHz
 36 What is the actual time that an US machine is creating a pulse?
 A. Duty factor
 B. Period
 C. Pulse period
 D. Pulse duration
 37 What is the significance of gray scale variation in the spectrum of a pulssed wave Doppler display?
 A. It represents the number of red blood cells creating the reflection
 B. It represents the velocity of red blood cells
 C. It represents the speed of red blood cells
 D. It represents the convergence of red blood cell lamina
 E. It determines the enseble length
 38 What is the production of deformation from voltage called?
 A. Piezoelectricity
 B. Impedance
 C. Cogeneration
 D. Flux
 39 What is the elimination of voltages that do not exceed a certain level?
 A. Amplification
 B. Decompensation
 C. Reject
 D. Demodulation
 40 How many data bits are needed to represent 46 gray shades?
 A. 46
 B. 5
 C. 6
 D. 8
 41 Which of the following is associated with cavitation?
 A. Thermal index
 B. Snell's Law
 D. Mechanical index
 42 All of the following are true of normal cavitation EXCEPT:
 A. Harmful bioeffects are commonly observed
 B. It is also known as inertial cavitation
 C. Only a 10% increase in pressure is needed to convert to this from stable cavitation
 D. Temperatures in the thousands of degreesare created
 E. It is consistent with shock waves
 43 The packet size in color Doppler refers to the number of :
 A. Pulses per second
 B. Sample volumes per scan line
 C. Scan lines per unit area
 D. Pulse - listen cycles per acoustic scan line
 E. Pulses required to create one frame
 44 A commonly used process for determining direction in a Doppler instrument is
 A. Zero crossing detection
 B. Autocorrelation
 D. Range gating
 E. Spectral analysis
 45 What is the maximum velocity limit for a 3 MHz CW Doppler unit operating at a depth of 4cm?
 A. 40 cm/s
 B. 200 cm/s
 C. 2.5 m/s
 D. 4 m/s
 E. None of the above
 46 What method is used to steer the color beam with a linear array transducer?
 A. Mechanical
 B. Electronic time delays
 C. Electronic voltage variation
 D. Apodization
 E. The color beam cannot be steered with a linear array transducer
 47 Increasing the wall filter during Doppler sampling will:
 A. Increase visibility of low velocity signals