Medical Physics ALL MCQs; 1st year QUESTION AND CORRECT ANSWER

Medical Physics ALL MCQs; 1st year QUESTION AND CORRECT ANSWER 1. Sound amplification in the outer ear (auditory canal)is affected by: a. Sound speed b. Sound pressure c. Sound amplitude - CORRECT ANSWER-b. Sound pressure 2. Prolonged exposure to loud noise can cause permanent damage to: a. The air conductivity (of the ear) b. The structure of the eardrum (tympanic membrane) c. Inner ear - CORRECT ANSWER-c. Inner ear 3. The loss of elasticity (stiffening) of the tympanic membrane will result in: a. Increase of air conductivity b. Decrease of hearing threshold c. Decrease in the binaural effect - CORRECT ANSWER-b. Decrease of hearing threshold 4. Sound intensity level (dB) and Loudness (phones) will have the same magnitude at the following frequency: a. 20 Hz b. 1000 Hz c. 20 KHz - CORRECT ANSWER-b. 1000 Hz 5. Refer to the equal-loudness curve above. At frequency of 4000 Hz the perceived sound is: a. Louder than at 1000 Hz b. The same as at 1000 Hz c. Softer than at 1000 Hz - CORRECT ANSWER-a. Louder than at 1000 Hz 6. Sound Intensity Level is proportional to the logarithm of the ratio of incoming to threshold intensity SIL = 10·Log (I/I0). If intensity is increased by a factor of 100, what is change in SIL? a. Increase by a factor of 10 (10 times) b. Double (2 times) c. Increase with 20 dB (plus 20dB) - CORRECT ANSWER-c. Increase with 20 dB (plus 20dB) 7. The sound intensity level in a room is 20 dB. A TV produces additional intensity level of 60 dB. What is the sound intensity in the room now? a. 80 dB b. 40 dB c. 60 dB - CORRECT ANSWER-c. 60 dB 8. Match the physical (objective) with the corresponding psychophysical (subjective) properties of the sound: (hint: multiple connections are possible) a. Frequency b. Intensity c. Acoustic spectrum 1. Timbre 2. Pitch 3. Loudness - CORRECT ANSWER-a. - 2.; b. - 3.; c. - 1. 9. Sound frequency is: a. Psychophysical property (subjective) b. Physical property (objective) c. Sound is measured in wavelength, and light is measured in frequency - CORRECT ANSWER-b. Physical property (objective) 10. The fundamental harmonic (frequency f0) in a complex sound is characterized by: a. The lowest frequency and highest amplitude b. The highest frequency and lowest amplitude c. The highest frequency and highest amplitude - CORRECT ANSWER-a. The lowest frequency and highest amplitude 11. The speed of sound is calculated by the Newton-Laplace formula √(K/ρ), where K is the stiffness coefficient, and ρ is the density of the material. If the density of the substance doubles, the speed of propagating sound wave will: a. Increase b. Decrease c. Depends on the frequency - CORRECT ANSWER-b. Decrease 12. What is the speed of sound in air? a. 330 m/s b. 900 m/s c. 1550 m/s - CORRECT ANSWER-a. 330 m/s 13. Does absorption of sound and the corresponding penetration depth depend on the wavelength? a. No b. It does. There is less absorption at longer wavelengths, and they propagate deeper c. It does. There is less absorption at shorter wavelengths, and they propagate deeper - CORRECT ANSWER-b. It does. There is less absorption at longer wavelengths, and they propagate deeper 14. Is it possible for internal organs to generate sounds that propagate to the skin, and are audible? a. No b. Yes, organs produce sounds that propagate through the tissues and are audible at the skin c. No, organs generate sounds but the waves are absorbed by the tissues and are inaudible at the skin - CORRECT ANSWER-b. Yes, organs produce sounds that propagate through the tissues and are audible at the skin 15. Noise can be defined as: a. Intense sound with constant frequency b. Directed sound waves with low intensity and changing modulation c. Superposition of random sound vibrations, with frequency and amplitude constantly changing in time. - CORRECT ANSWER-c. Superposition of random sound vibrations, with frequency and amplitude constantly changing in time. 16. Damping oscillations are: a. Oscillations with increasing amplitude b. Oscillations with decreasing amplitude c. Not related to amplitude - CORRECT ANSWER-b. Oscillations with decreasing amplitude 17. If the amplitude of a wave doubles (x2), what would happen to the period? a. It will double b. It will be halved c. There will be no change - CORRECT ANSWER-c. There will be no change 18. In which of the following mediums, sound waves cannot propagate? a. Gases b. Liquids c. Vacuum - CORRECT ANSWER-c. Vacuum 19. Which of the following waves are NOT mechanical? a. Light b. Water waves c. Sound waves - CORRECT ANSWER-a. Light 20. A propagating sound wave transfers: a. Energy b. Matter c. Both, energy and matter - CORRECT ANSWER-a. Energy 21. Which of the following factors has the most significant effect on the speed of propagation of sound waves? a. Elastic properties of the medium b. The size of the wave front c. The pressure in gaseous environment - CORRECT ANSWER-a. Elastic properties of the medium 22. Sound waves are: a. Mechanical waves b. Electromagnetic waves c. Gravitational waves - CORRECT ANSWER-a. Mechanical waves 23. The speed of sound (in non-dispersive medium): a. Depends on the properties of the propagating medium b. Is always constant, independent of the medium c. Decreases as sound moves away from the its source - CORRECT ANSWER-a. Depends on the properties of the propagating medium 24. Human ear is most sensitive to frequencies (refer to equal-loudness curve): a. Below 1000 Hz b. From 2000 Hz to 5000 Hz c. Above 5000 Hz - CORRECT ANSWER-b. From 2000 Hz to 5000 Hz 25. What is the meaning of 0 dB? a. There is no sound b. The sound is below hearing threshold level c. The sound is at threshold reference level - CORRECT ANSWER-c. The sound is at threshold reference level 26. Timbre is: a. Physical (objective) property of sound b. Psychophysical (subjective) sound property c. Type of wood found in North America - CORRECT ANSWER-b. Psychophysical (subjective) sound property 27. The pitch of sound depends mostly on: a. Intensity of sound b. Sound pressure c. Sound frequency - CORRECT ANSWER-c. Sound frequency 28. Which of the following does NOT have relevance to the reflection/transmission of sound waves? a. The acoustic impedance of substances at the boundary b. The colors of substances near the boundary area c. The cross sectional area of the boundary surface - CORRECT ANSWER-b. The colors of substances near the boundary area 29. Timbre is related to: a. Harmonic overtones b. Wooden instruments c. Falling trees - CORRECT ANSWER-a. Harmonic overtones 30. Weber-Fechner law (in psychophysics) describes a logarithmic relationship between the intensity of a sound wave and....: a. Acoustic pressure b. The sound pitch c. The perception of loudness - CORRECT ANSWER-c. The perception of loudness 31. Intensity is defined as: a. Power per area b. Power per time c. Energy per time - CORRECT ANSWER-a. Power per area 32. When sound wave travels across two materials with similar acoustic impedance, at the boundary surface there will be: a. similar amounts of transmission and reflection b. more transmission and less reflection c. less transmission and more reflection - CORRECT ANSWER-b. more transmission and less reflection 33. The acoustic impedance Z of a substance is defined as the product of: a. The density and the atomic number of the element: ρZ b. The density and the speed of sound: ρv c. The temperature and the speed of sound: tv - CORRECT ANSWER-b. The density and the speed of sound: ρv 34. Why can't we hear voices (speech) when submerged under water? a. Most of the sound is reflected at the air/water boundary b. Sound waves do not propagate under water c. Ear canals are clogged with water - CORRECT ANSWER-a. Most of the sound is reflected at the air/water boundary 35. What property of sound is measured in decibels (dB)? a. Wavelength b. Intensity level c. Loudness - CORRECT ANSWER-b. Intensity level 36. If the period of a wave is 0.02 s, what is its frequency? (Hint: how often does it vibrate in one second?) a. 200 Hz b. 100 Hz c. 50 Hz - CORRECT ANSWER-c. 50 Hz 37. A person screams in the mountain and hears the echo after 2 seconds. How far was the cliff that caused the reflection of the sound (echo)? a. 1020 m b. 340m c. 680m - CORRECT ANSWER-b. 340m 38. Which of the following properties of sound is measured in Hertz (Hz)? a. Power b. Amplitude c. Frequency - CORRECT ANSWER-c. Frequency 39. When sound wave propagates between two media with similar impedance, there will be: a. Equal amounts of transmission and reflection b. Be more transmission and less reflection c. Be more reflection and less transmission - CORRECT ANSWER-b. Be more transmission and less reflection 40. The human ear is sensitive to frequencies in the range: a. 20 Hz - 20 MHz b. 200 Hz - 20 kHz c. 20 Hz - 2000 Hz - CORRECT ANSWER-c. 20 Hz - 2000 Hz 41. What are the SI units for loudness? a. Sone b. Phon c. dB - CORRECT ANSWER-b. Phon 42. The speed of sound in the human body is approximately: a. 330 m/s b. 1500 m/s c. 6000 m/s - CORRECT ANSWER-b. 1500 m/s 43. The audiogram is a method for hearing loss evaluation by measuring the threshold hearing intensity of sound for different: a. Frequencies b. Wavelengths c. Amplitudes - CORRECT ANSWER-a. Frequencies 44. Pure tone is characterized by: a. Deviation from the equilibrium is proportional to the frequency b. Constant velocity vector c. Constant frequency - CORRECT ANSWER-c. Constant frequency 45. When sound wave travels from air into the human body, what happens to its speed? a. Increases, because tissue has higher acoustic impedance b. Decreases, because tissue has lower acoustic impedance c. It doesn't change because the speed of sound is constant - CORRECT ANSWER-a. Increases, because tissue has higher acoustic impedance 46. Doppler shift applies to: a. All wave phenomena b. Ultrasound c. Infrared EM waves - CORRECT ANSWER-a. All wave phenomena 47. The contact gel used in ultrasonography (echography) is for: a. Protection of the body from harmful ultrasound b. Efficient transmission of sound waves into the tissue c. Improvement of skin elasticity in the area of study - CORRECT ANSWER-b. Efficient transmission of sound waves into the tissue 48. In medical imaging, Doppler echography is most appropriate for: a. Deep body targets b. Moving body targets c. Surface targets - CORRECT ANSWER-b. Moving body targets 49. Which of the following waves do cannot propagate in vacuum? a. Radiowaves b. X-rays c. Ultrasound - CORRECT ANSWER-c. Ultrasound 50. In what form is the information received with Doppler Echography displayed? a. By sound b. By one dimensional image c. By two dimensional image with artificial coloring - CORRECT ANSWER-c. By two dimensional image with artificial coloring 51. Doppler frequency (shift) is: a. The infrared spectrum of light, studied by Doppler b. The frequency generated by ultrasonic transducer c. The difference between emitted and reflected (received) frequency between to objects in relative motion. - CORRECT ANSWER-c. The difference between emitted and reflected (received) frequency between to objects in relative motion. 52. For which of the following numerical Doppler frequency shifts is the blood speed the highest? a. 1210 Hz b. 800 Hz c. 1530 Hz - CORRECT ANSWER-c. 1530 Hz 53. Is it possible to tell the direction of motion of erythrocytes from the sign of the Doppler shift ∆f = f - f0? a. Yes, when ∆f > 0 erythrocytes move towards the transducer b. Yes, when ∆f > 0erythrocytes move away from the transducer c. No, the sign of ∆f does not tell the direction of motion - CORRECT ANSWER-a. Yes, when ∆f > 0 erythrocytes move towards the transducer 54. If shorter wavelengths of ultrasound are less penetrating in human tissue, then which of the following frequencies is most appropriate for DEEP tissue and organ imaging? a. 8 MHz b. 3 MHz c. 20 MHz - CORRECT ANSWER-b. 3 MHz 55. Doppler shift is defined as: a. The frequency difference between emitted and received signals for observers at relative motion b. The difference in acoustic impedance between two transmitting mediums c. The intensity difference between emitted and reflected waves - CORRECT ANSWER-a. The frequency difference between emitted and received signals for observers at relative motion 56. At what angle (Θ) to the surface of the body should the ultrasonic probe be applied in order to gain a maximum Doppler shift? Consider that Doppler shift is proportional to cos (Θ). a. Θ = 45⁰ (cos 45 = 0.7) b. Θ = 90⁰ (cos 90 = 0) c. Θ = 60⁰ (cos 60 = 0.5) - CORRECT ANSWER-a. Θ = 45⁰ (cos 45 = 0.7) 57. The speed of ultrasound in human tissue depends on: a. The properties of the tissue b. The properties of the apparatus c. The speed of (ultra)sound does not depend on the tissue - CORRECT ANSWER-a. The properties of the tissue 58. The so called "reverse piezoelectric effect" finds application in: a. Ultrasound generation b. X-ray tubes c. Lasers - CORRECT ANSWER-a. Ultrasound generation 59. Ultrasound can propagate through: a. Vacuum b. Matter c. Everywhere where light propagates - CORRECT ANSWER-b. Matter 60. Phonophoresis is: a. Therapeutic application of ultrasound b. Diagnostic application of ultrasound c. Method for sterilization - CORRECT ANSWER-a. Therapeutic application of ultrasound 61. Infrasound of certain frequency and intensity can: a. Damage internal organs b. Increase temperature of tissues c. Rearrange water molecules - CORRECT ANSWER-a. Damage internal organs 62. Infrasound CANNOT propagate through: a. Soft tissue b. Bones c. Vacuum - CORRECT ANSWER-c. Vacuum 63. Choose the correct statement: a. Ultrasound is completely harmless for humans and animals b. Sound reflection depends on the transparency of the medium c. Sound impedance does not depend on frequency (for linear mediums) - CORRECT ANSWER-c. Sound impedance does not depend on frequency (for linear mediums) 64. Choose the correct range: a. Audible sound: 103 Hz—106 Hz b. Infrasound: 3 Hz—10 Hz c. Ultrasound: 10 kHz—10 kHz - CORRECT ANSWER-b. Infrasound: 3 Hz—10 Hz 65. The resonant frequency of the vestibular system is in the range of: a. Ultrasound b. Infrasound c. Ultraviolet - CORRECT ANSWER-b. Infrasound 66. The direct piezoelectric effect is used for: a. Ultrasound detectors b. Ultrasound generators c. Electrophoresis - CORRECT ANSWER-a. Ultrasound detectors 67. Piezoelectric effect is defined as: a. Electric polarization of solids under mechanical stress b. Electro-mechanical coupling of objects falling off the tower of Pisa c. Electric polarization in a solid due to temperature gradient. - CORRECT ANSWER-a. Electric polarization of solids under mechanical stress 68. Does human tissue exhibit piezoelectric properties? a. No, the human body exhibits only capacitive properties b. No, piezoelectric properties are observed in inorganic crystals c. Yes, tissue such a collagen has piezoelectric properties - CORRECT ANSWER-c. Yes, tissue such a collagen has piezoelectric properties 69. Which statement is correct? a. The size of the ultrasonic equipment (echograph) influences the acoustic density of imaged tissue. b. The precision of the ultrasonic instrument does not have an effect on the quality of received images c. The ultrasonic image, displayed on the monitor, represents the acoustic density of studied tissues. - CORRECT ANSWER-c. The ultrasonic image, displayed on the monitor, represents the acoustic density of studied tissues. 70. Mechanical waves with frequency above 20 kHz are called: a. Infrasound b. Ultrasound c. P-waves - CORRECT ANSWER-b. Ultrasound 71. Infrasound is: a. Electromagnetic waves with frequency under 20 Hz b. Mechanical waves with frequency above 20 Hz c. None of the above - CORRECT ANSWER-c. None of the above 72. If Δf is the change in frequency between emitted and received ultrasound signals due to Doppler effect during measurement of the linear speed of blood, then: a. The speed of blood relative to the stationary transducer (emitter and receiver) is as much great as Δf is greater b. Blood motion does not affect Δf c. The speed of blood relative to the stationary transducer is greater when Δf is smaller. - CORRECT ANSWER-a. The speed of blood relative to the stationary transducer (emitter and receiver) is as much great as Δf is greater 73. Which natural science studies infrasound? a. Pediatrics b. Seismology c. Dental medicine - CORRECT ANSWER-b. Seismology 74. Mechanical waves used for destruction of kidney stones, in procedure called "lithotripsy", cause minimal damage to surrounding tissues because: a. Mechanical waves do not propagate through the surrounding tissue b. Acoustic pressure in the surrounding tissue is greatly reduced compared tothe pressure induced in the kidney stones c. Mechanical waves do not have negative effect on soft tissue - CORRECT ANSWERb. Acoustic pressure in the surrounding tissue is greatly reduced compared tothe pressure induced in the kidney stones 75. Ultrasound waves propagate through human tissue as: a. Longitudinal waves b. Transverse waves c. Both, longitudinal and transverse modes - CORRECT ANSWER-a. Longitudinal waves 76. Can humans sense infrasound waves? a. Only when the intensity of the wave is sufficiently high for the ear to detect b. No, that's why they are called infra-sound c. They can be sensed as vibrations by the tactile receptors of the skin - CORRECT ANSWER-c. They can be sensed as vibrations by the tactile receptors of the skin 77. The resonant frequency of the internal organs is in the range of: a. 10 MHz b. Infrasound c. Ultrasound - CORRECT ANSWER-b. Infrasound 78. Which of the following is used in Doppler echography? a. Magnetic resonance b. Vacuum tubes c. Piezoelectric effect - CORRECT ANSWER-c. Piezoelectric effect 79. What units are used to measure blood pressure with aneroid manometer? a. mmHg, kPa b. mmHg, atm c. N.m^-2, Torr - CORRECT ANSWER-b. mmHg, atm 80. What is the predominant type of blood follow in the arteries of a healthy person? a. Turbulent b. Laminar c. Transitional - CORRECT ANSWER-b. Laminar 81. Blood pressure on the walls of blood vessels is compensated (counterbalanced) by the elasticity of blood vessels, and by the air pressure. If the reading of the sphygmomanometer during a systole is 120 mmHg and air pressure is 760 mmHg, what is the actual pressure that blood exerts on the walls of arteries? a. 90 mmHg b. 640 mmHg c. 880 mmHg - CORRECT ANSWER-c. 880 mmHg 82. Pulse pressure is defined as: a. The difference between systolic and diastolic pressures b. The difference between systolic and atmospheric pressures c. The average of diastolic and systolic pressures - CORRECT ANSWER-a. The difference between systolic and diastolic pressures 83. What is the most precise definition of blood pressure? a. The pressure in the cardio-vascular system b. The pressure exerted by blood on the walls of blood vessels c. The pressure in the arteries - CORRECT ANSWER-b. The pressure exerted by blood on the walls of blood vessels 84. When blood pressure is measured with a stethoscope, at what point is the systolic pressure detected? a. At the loudest sound b. At the first sound c. When the sound disappears - CORRECT ANSWER-b. At the first sound 85. When blood pressure is measured with a stethoscope, at what point is the diastolic pressure detected? a. At the loudest sound b. At the first sound c. When sounds disappear - CORRECT ANSWER-c. When sounds disappear 86. What is the variation of blood pressure across the cardio-vascular system: a. It decrease linearly from arteries to veins b. It oscillates between diastolic and systolic but stays mostly the same c. It decreases non-linearly with the greatest drop at the capillaries - CORRECT ANSWER-c. It decreases non-linearly with the greatest drop at the capillaries 87. What property of blood is characterized by the Reynolds number? a. Blood viscosity b. Blood speed c. Type of blood flow: laminar or turbulent - CORRECT ANSWER-c. Type of blood flow: laminar or turbulent 88. Cardiac resonant frequency in the range of: a. Infrasound b. Ultrasound c. Infrared - CORRECT ANSWER-a. Infrasound 89. What causes the Korotkoff sounds? a. High blood pressure b. Turbulent flow of blood around constrictions c. High pulse rate - CORRECT ANSWER-b. Turbulent flow of blood around constrictions 90. The speed of arterial pulse wave depends mostly on: a. The hematocrit b. The elasticity of blood vessels c. The cross section of blood vessels - CORRECT ANSWER-b. The elasticity of blood vessels 91. Gas embolism (clogging of blood vessel) can be explained with: a. Reynolds number (Re) b. Dynamic viscosity of blood (η) c. Laplace pressure (Δp) - CORRECT ANSWER-c. Laplace pressure (Δp) 92. Ideal liquids are defined as: a. Lacking internal friction b. Molecular cohesive forces c. Surface tension and activity - CORRECT ANSWER-a. Lacking internal friction 93. What quantity is transferred when there is internal friction? a. Mass b. Impulse c. Charge - CORRECT ANSWER-b. Impulse 94. Which of the following parameters is the most informative for the blood supply of a given organ? a. Arterial pressure b. The speed of blood c. Blood flow - CORRECT ANSWER-c. Blood flow 95. A necessary condition for internal friction (viscous force) in fluid dynamics is: a. Concentration gradient b. Velocity gradient c. Electric charge gradient (potential difference) - CORRECT ANSWER-b. Velocity gradient 96. Laplace pressure Δр does NOT depend on: a. The radius of the surface b. Atmospheric pressure c. The coefficient of surface tension σ - CORRECT ANSWER-b. Atmospheric pressure 97. Which of the following parameters of the vascular system have the greatest effect on blood flow resistance? a. Viscosity of blood b. Volumetric flow rate c. Radius of vessels lumen - CORRECT ANSWER-c. Radius of vessels lumen 98. Ideal (perfect) fluid is defined as: a. Incompressible and without viscosity b. High liquidity and low density c. Constant velocity and surface tension - CORRECT ANSWER-a. Incompressible and without viscosity 99. Where in the cardiovascular system is the blood pressure at minimum? a. In the capillaries b. In the veins c. In the aorta - CORRECT ANSWER-b. In the veins 100. The volumetric flow rate Q =dV/dt of blood in the cardiovascular system is: a. Constant at any given time b. Greater in the pulmonary circuit c. Variable: it decreases from arteries to capillaries to veins - CORRECT ANSWER-a. Constant at any given time 101. Linear velocity of blood in the cardiovascular system is: a. Constant at any given time b. Variable: decreases from arteries to capillaries to veins c. Variable: lowest in the capillaries - CORRECT ANSWER-c. Variable: lowest in the capillaries 102. Which of the following formulas relates volumetric flow rate Q to linear speed v and surface area S of a fluid in a closed circuit (blood)? a. V = Q S b. Q = v S c. S = Q v - CORRECT ANSWER-b. Q = v S 103. Does heart rate change with aging? a. Yes, increases b. Yes, decreases c. Does not change - CORRECT ANSWER-b. Yes, decreases 104. Most of the energy expended by the heart muscle during cardiac cycle goes into: a. overcoming the pressure in the aorta b. kinetic energy of moving blood c. heat generation - CORRECT ANSWER-a. overcoming the pressure in the aorta 105. Which of the following expressions is the formula for the propagation speed of pulsewaves? Where: E in the elastic modulus of vessels, d is the thickness of blood vessels, r is the radius of the lumen, and ρ is the blood density. a. v = k. (E.d/2rρ)^(1/2) b. v = k. (E.d/2rρ) c. v = k. (rρ/2Ed)^(1/2) - CORRECT ANSWER-a. v = k. (E.d/2rρ)^(1/2) 106. How does the linear speed of blood compare to the speed of a pulse wave? a. They are identical b. Blood moves faster than the pulse wave c. Pulse wave moves faster than blood - CORRECT ANSWER-c. Pulse wave moves faster than blood 107. The pulse wave propagates, and is detectible in: a. The entire cardiovascular system b. In the arteries c. In the capillaries - CORRECT ANSWER-b. In the arteries 108. In the cardiovascular system (CVS) of healthy young person, turbulent flow is found: a. In the entire CVS b. In the capillaries c. In the Aortic arch - CORRECT ANSWER-c. In the Aortic arch 109. Which of the following formulas relate heart rate (HR), stroke volume (SV), and cardiac output (CO)? a. CO = HR x SV b. SV = HR x CO Where the respective units are HR [bpm], SV [liters], and CO [liters/min] c. HR = CO x SV - CORRECT ANSWER-a. CO = HR x SV 110. Reynolds number (Re) is dimensionless quantity used to: a. Determine types of mechanical wave phenomena: infrasound or ultrasound b. Determine the type of fluid flow: laminar or turbulent c. Determine the type of x-rays: soft or hard - CORRECT ANSWER-b. Determine the type of fluid flow: laminar or turbulent 111. During turbulent motion, particles move: a. Parallel and unidirectional, in coaxial cylindrical layers. Where each layer has a constant speed, which increases away from the vessel walls and toward the central axis. b. Disorderly c. Parallel and unidirectional, in coaxial cylindrical layers. Where each layer has a constant speed, which increases away from the center axis and toward the vessel walls. - CORRECT ANSWER-b. Disorderly 112. Is power efficiency of the heart muscle affected by the type of blood flow in the vascular system (turbulent or laminar)? a. Yes, the efficiency is greater for laminar flow b. Efficiency is not affected c. Yes, turbulent flow leads to better efficiency - CORRECT ANSWER-a. Yes, the efficiency is greater for laminar flow 113. For laminar blood flow the relationship between the change in blood pressure (∆P) and the change in volumetric flow rate (∆Q) is as follows: a. ∆Q ~ ∆P (∆Q is proportional to ∆P) b. ∆Q ~ ∆P/3 c. ∆Q ~ (∆P)2 - CORRECT ANSWER-a. ∆Q ~ ∆P (∆Q is proportional to ∆P) 114. For turbulent blood flow the relationship between the change in blood pressure (∆P) and the change in volumetric flow rate (∆Q) is as follows: a. ∆Q ~ ∆P (reads: ∆Q is proportional to ∆P) b. ∆Q ~ (∆P)^2 c. ∆Q ~ ∆P/5 - CORRECT ANSWER-b. ∆Q ~ (∆P)^2 115. Speed of pulse waves in atherosclerotic vessels is: a. Decreased (slower) b. Increased (faster) c. Unaffected - CORRECT ANSWER-b. Increased (faster) 116. Hemodialysis is a method for: a. Determination of serum proteins by blood dialysis b. Removing toxins from patient's blood c. investigating brain hemodynamics - CORRECT ANSWER-b. Removing toxins from patient's blood 117. Does speed of dialysis depend on the conductance of the membrane? a. Yes, high conductance relates to faster dialysis b. Yes, high conductance relates to slower dialysis c. There is no correlation between membrane conductance and the rate of dialysis - CORRECT ANSWER-a. Yes, high conductance relates to faster dialysis 118. What is the purpose of the air micro-bubble detector in the hemodialysis machine? a. To check the O2 level in the blood b. To check the levels of CO2 in the blood c. To prevent gas (air) embolism - CORRECT ANSWER-c. To prevent gas (air) embolism 119. Gas embolism of blood vessels (blockage) can be explained by the: a. Reynolds number Re b. Blood viscosity η c. Laplace pressure ∆p - CORRECT ANSWER-c. Laplace pressure ∆p 120. Toxin concentrations in blood during Hemodialysis can be modeled with an exponential decay law. Using the graph below (Fig. 2, wrong labels here, look up in original mcq doc), estimate the time it takes for toxin concentration to decrease from 60 to 40 percent of the original. a. 5h b. 2.5 min c. 2.5h - CORRECT ANSWER-c. 2.5h 121. During hemodialysis, the proper concentration of electrolytes in the dialysate (dialyzing solution) is evaluated continuously by measuring the conductivity of the solution. If conductivity DECREASES, that means: a. There are more electrolytes b. There are air bubbles c. There are less electrolytes - CORRECT ANSWER-c. There are less electrolytes 122. What type of membrane is commonly used for hemodialysis? a. Artificial semipermeable membrane b. Organic semipermeable membrane c. Impermeable membrane - CORRECT ANSWER-a. Artificial semipermeable membrane 123. In the dialysis column, blood and dialysate travel in: a. The same direction b. Opposite directions c. Blood travels while the dialysate stays still - CORRECT ANSWER-b. Opposite directions 124. During hemodialysis, why is it important to keep blood pressure higher than dialysate pressure? a. To force toxic substances from the blood into the dialysate b. To prevent backflow of substances from dialysate solution into the blood c. To facilitate ultrafiltration (remove excess water out of the blood stream) - CORRECT ANSWER-c. To facilitate ultrafiltration (remove excess water out of the blood stream) 125. During hemodialysis, is it necessary for the dialysate solution to be hypertonic? a. Yes, because this way ions will flow back into the blood b. Not necessary, because it could can have negative effects on the dialysis c. It is necessary, in order not to slow down the dialysis - CORRECT ANSWER-b. Not necessary, because it could can have negative effects on the dialysis 126. Osmosis is: a. Movement of solvent through a semipermeable membrane into a region with higher solute concentration b. Movement of solute through a semipermeable membrane into a region with higher solvent concentration c. Diffusion of water - CORRECT ANSWER-a. Movement of solvent through a semipermeable membrane into a region with higher solute concentration 127. Which of the following is absolutely necessary for the process of osmosis to occur? a. Water b. Semipermeable membrane c. Sodium ions - CORRECT ANSWER-b. Semipermeable membrane 128. If a semiconductor is brought down to temperature of absolute zero (0 Kelvin), it will become: a. A conductor b. A superconductor c. An insulator - CORRECT ANSWER-c. An insulator 129. According to Band Theory of Solids, what can be said about the relationship between band-gap width and the tendency of material to conduct electricity? a. The greater the band-gap width the less conductive is the material b. The lesser the band-gap width the more insulating is the material c. The greater the band-gap width the more conductive is the material - CORRECT ANSWER-a. The greater the band-gap width the less conductive is the material 130. According to Band Theory of Solids, what can be said about P- and N- type conductivity with regard to the location of the electron bands? a. P and N type conductivities are in the conduction band b. P-type conductivity is in the conduction band, and N-conductivity is in the valence band c. P-type conductivity is in the valence band, and N-conductivity is in the conduction band - CORRECT ANSWER-c. P-type conductivity is in the valence band, and Nconductivity is in the conduction band 131. What are the respective current carriers for N- and P-type conductivity? a. Electrons b. P-type carriers are "holes", and N-type are electrons c. P-type are positrons, and N-type are "holes" - CORRECT ANSWER-b. P-type carriers are "holes", and N-type are electrons 132. Typical semiconductors such as Silicon and Germanium are group IV elements. Choose the correct statement regarding the doping and the type of conductivity (N or P) acquired, after doping: a. P-type conductivity is achieved by doping with elements from group V, and N-type conductivity is achieved by doping with elements from group III b. Both types are achieved from doping with group IV c. P-type conductivity is achieved by doping with elements from group III, and N-type conductivity is achieved by doping with elements from group V - CORRECT ANSWERc. P-type conductivity is achieved by doping with elements from group III, and N-type conductivity is achieved by doping with elements from group V 133. What is the relationship between N- and P- type charge carriers for intrinsic (undoped) semiconductors? a. N = P b. N > P c. N < P - CORRECT ANSWER-a. N = P 134. For semiconducting materials, charge carrier species called holes are best described as: a. Electrons moving in opposite direction b. Protons c. Virtual particles signifying electron vacancy - CORRECT ANSWER-c. Virtual particles signifying electron vacancy 135. In doped (extrinsic) semiconductors, the predominant current carriers are called majority charge carriers, and secondary carriers are called minority. Which statement is true for N-and P-type semiconductors: a. In N-type semiconductors, electrons are majority carriers and holes are minority carriers b. In P-type semiconductors, majority carriers are electrons, and minority charge carriers are holes c. In N-type semiconductors, both types of carriers are equally present - CORRECT ANSWER-a. In N-type semiconductors, electrons are majority carriers and holes are minority carriers 136. Transistors are made of N- and P-type semiconductors arranged in a such way that: a. There are two p-n junctions b. There are three p-n junctions c. There is one p-n junction - CORRECT ANSWER-a. There are two p-n junctions 137. The two main functions of the transistor are: a. Polarizer and oscillator b. Amplifier and switch c. Rectifier and attenuator - CORRECT ANSWER-b. Amplifier and switch 138. Choose the FALSE statement. Electrical amplifiers are used for: a. Voltage b. Frequency c. Current - CORRECT ANSWER-b. Frequency 139. The magnitude of electrical impedance of biological tissues is the (Pythagorean) sum of: a. Resistance and capacitive reactance b. Inductive and capacitive reactance c. Resistance and inductive reactance - CORRECT ANSWER-a. Resistance and capacitive reactance 140. What type of transducer is the piezoelectric crystal in ultrasonic equipment, when working in receiving mode? a. Generative transducer b. Both, generative and parametric c. Parametric transducer - CORRECT ANSWER-a. Generative transducer 141. The "band gap" in semiconductor theory is defined as: a. The distance between valence and conduction bands b. The frequency gap between AM and FM radio bands c. The energy gap between valence and conduction bands - CORRECT ANSWER-c. The energy gap between valence and conduction bands 142. When temperature increases, the band gap in a semiconductor: a. Increases, due to increased kinetic energy of atoms b. Remains the same, because electrons are bound in their orbits c. Decreases, due to electron-phonon interactions - CORRECT ANSWER-c. Decreases, due to electron-phonon interactions 143. When semiconductor is doped with element of lower valence (P-type doping) it becomes a donor (gives off electrons) and there is a shift in the energy band gap. The new electron levels are: a. Near the middle of the band gap b. Near the conduction band c. Near the valence band - CORRECT ANSWER-c. Near the valence band 144. When temperature increases, the conductivity of semiconductors: a. Increases b. Decreases c. Remains the same - CORRECT ANSWER-b. Decreases 145. When semiconductor is doped with element of higher valence (N-type doping) it becomes an acceptor (takes electrons) and there is a shift in the energy band gap. The new electron levels are: a. Near the middle of the band gap b. Near the conduction band c. Near the valence band - CORRECT ANSWER-c. Near the valence band 146. When Silicon (Si) is doped with one of the following elements, it acquires P-type conductivity (holes are the majority carriers). Choose the one: a. Boron (B), valence III b. Phosphorus (P), valence V c. Tin (Sn), valence IV - CORRECT ANSWER-a. Boron (B), valence III 147. Electric circuit components composed of single p-n junction are called: a. Capacitors b. Transistors c. Diodes - CORRECT ANSWER-c. Diodes