Physics MCQs (3) PDF

Practical № 2 Date: Signature: Audiogram – a method for diagnostics of the hearing apparatus 1. Sound amplification in the outer ear (auditory canal)is affected by: a. Sound speed b. Sound pressure c. Sound amplitude 2. Prolonged...

Practical № 2 Date: Signature: Audiogram – a method for diagnostics of the hearing apparatus 1. Sound amplification in the outer ear (auditory canal)is affected by: a. Sound speed b. Sound pressure c. Sound amplitude 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 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 4. Sound intensity level (dB) and Loudness (phones) will have the same magnitude at the following frequency: (ref. the equal-loudness graph, Fig.1) a. 20 Hz b. 1000 Hz c. 20 KHz Figure 1 Equal Loudness Curve 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 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)  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 8. Match the physical (objective) with the corresponding psychophysical (subjective) properties of the sound: (hint: multiple connections are possible) a. Frequency a. Timbre b. Intensity b. Pitch c. Acoustic spectrum c. Loudness 9. Sound frequency is: a. Psychophysical property (subjective) b. Physical property (objective) c. Sound is measured in wavelength, and light is measured in frequency 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 11. The speed of sound is calculated by the Newton-Laplace formula √ , 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 12. What is the speed of sound in air? a. 330 m/s b. 900 m/s c. 1550 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 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 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. 16. Damping oscillations are: a. Oscillations with increasing amplitude b. Oscillations with decreasing amplitude c. Not related to 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 18. In which of the following mediums, sound waves cannot propagate? a. Gases b. Liquids c. Vacuum 19. Which of the following waves are NOT mechanical? a. Light b. Water waves c. Sound waves 20. A propagating sound wave transfers: a. Energy b. Matter c. Both, energy and matter 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 22. Sound waves are: a. Mechanical waves b. Electromagnetic waves c. Gravitational 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 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 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 26. Timbre is: a. Physical (objective) property of sound b. Psychophysical (subjective) sound property c. Type of wood found in North America 27. The pitch of sound depends mostly on: a. Intensity of sound b. Sound pressure 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 29. Timbre is related to: a. Harmonic overtones b. Wooden instruments c. Falling trees 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 31. Intensity is defined as: a. Power per area b. Power per time c. Energy per time 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 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 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 35. What property of sound is measured in decibels (dB)? a. Wavelength b. Intensity level c. Loudness 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 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 38. Which of the following properties of sound is measured in Hertz (Hz)? a. Power b. Amplitude 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 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 41. What are the SI units for loudness? a. Sone b. Phon c. dB 42. The speed of sound in the human body is approximately: a. 330 m/s b. 1500 m/s c. 6000 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 44. Pure tone is characterized by: a. Deviation from the equilibrium is proportional to the frequency b. Constant velocity vector 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 Practical № 3 Date: Signature: Physical basis of Doppler ultrasound imaging 46. Doppler shift applies to: a. All wave phenomena b. Ultrasound c. Infrared EM waves 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 48. In medical imaging, Doppler echography is most appropriate for: a. Deep body targets b. Moving body targets c. Surface targets 49. Which of the following waves do cannot propagate in vacuum? a. Radiowaves b. X-rays 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 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. 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 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 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 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 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) 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 58. The so called “reverse piezoelectric effect” finds application in: a. Ultrasound generation b. X-ray tubes c. Lasers 59. Ultrasound can propagate through: a. Vacuum b. Matter c. Everywhere where light propagates 60. Phonophoresis is: a. Therapeutic application of ultrasound b. Diagnostic application of ultrasound c. Method for sterilization 61. Infrasound of certain frequency and intensity can: a. Damage internal organs b. Increase temperature of tissues c. Rearrange water molecules 62. Infrasound CANNOT propagate through: a. Soft tissue b. Bones 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) 64. Choose the correct range: a. Audible sound: 103 Hz—106 Hz b. Infrasound: 3 Hz—10 Hz c. Ultrasound: 10 kHz—10 kHz 65. The resonant frequency of the vestibular system is in the range of: a. Ultrasound b. Infrasound c. Ultraviolet 66. The direct piezoelectric effect is used for: a. Ultrasound detectors b. Ultrasound generators c. Electrophoresis 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. 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 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. 70. Mechanical waves with frequency above 20 kHz are called: a. Infrasound b. Ultrasound c. P-waves 71. Infrasound is: a. Electromagnetic waves with frequency under 20 Hz b. Mechanical waves with frequency above 20 Hz 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. 73. Which natural science studies infrasound? a. Pediatrics b. Seismology c. Dental medicine 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 75. Ultrasound waves propagate through human tissue as: a. Longitudinal waves b. Transverse waves c. Both, longitudinal and transverse modes 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 77. The resonant frequency of the internal organs is in the range of: a. 10 MHz b. Infrasound c. Ultrasound 78. Which of the following is used in Doppler echography? a. Magnetic resonance b. Vacuum tubes c. Piezoelectric effect Practical № 4 Date: Signature: Comparison of blood pressure values measured by two techniques – sphygmomanometry and oscillotonometry 79. What units are used to measure blood pressure with aneroid manometer? a. mmHg, kPa b. mmHg, atm c. N.m-2, Torr 80. What is the predominant type of blood follow in the arteries of a healthy person? a. Turbulent b. Laminar c. Transitional 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 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 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 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 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 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 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 88. Cardiac resonant frequency in the range of: a. Infrasound b. Ultrasound c. Infrared 89. What causes the Korotkoff sounds? a. High blood pressure b. Turbulent flow of blood around constrictions c. High pulse rate 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 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) 92. Ideal liquids are defined as: a. Lacking internal friction b. Molecular cohesive forces c. Surface tension and activity 93. What quantity is transferred when there is internal friction? a. Mass b. Impulse c. Charge 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 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) 96. Laplace pressure Δр does NOT depend on: a. The radius of the surface b. Atmospheric pressure c. The coefficient of surface tension σ 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  98. Ideal (perfect) fluid is defined as: a. Incompressible and without viscosity b. High liquidity and low density c. Constant velocity and surface tension 99. Where in the cardiovascular system is the blood pressure at minimum? a. In the capillaries b. In the veins c. In the aorta 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 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 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 103. Does heart rate change with aging? a. Yes, increases b. Yes, decreases c. Does not change 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 105. Which of the following expressions is the formula for the propagation speed of pulse waves? Where: E in the elastic modulus of vessels, d is the thickness a. v = k. (E.d/2rρ)1/2 b. v = k. (E.d/2rρ) of blood vessels, r is the radius of the lumen, and ρ is the 1/2 c. v = k. (rρ/2Ed) blood density. 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 107. The pulse wave propagates, and is detectible in: a. The entire cardiovascular system b. In the arteries c. In the capillaries 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 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 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 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. 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 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)2 114. 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/5 115. Speed of pulse waves in atherosclerotic vessels is: a. Decreased (slower) b. Increased (faster) c. Unaffected Practical № 5 Date: Signature: Physical basis of hemodialysis. Hemodialyzer 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 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 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 119. Gas embolism of blood vessels (blockage) can be explained by the: a. Reynolds number Re b. Blood viscosity η 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), 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 Figure 2 121. 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 122. What type of membrane is commonly used for hemodialysis? a. Artificial semipermeable membrane b. Organic semipermeable membrane c. Impermeable 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 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) 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 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 127. Which of the following is absolutely necessary for the process of osmosis to occur? a. Water b. Semipermeable membrane c. Sodium ions Practical № 6 Date: Signature: Transformation of non-electrical quantities. Calibration of semiconductor, thermometer and photoelement. 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 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 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 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” 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 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 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 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 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 137. The two main functions of the transistor are: a. Polarizer and oscillator b. Amplifier and switch c. Rectifier and attenuator 138. Choose the FALSE statement. Electrical amplifiers are used for: a. Voltage b. Frequency c. Current 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 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 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 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 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 144. When temperature increases, the conductivity of semiconductors: a. Increases b. Decreases c. Remains the same 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 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 147. Electric circuit components composed of single p-n junction are called: a. Capacitors b. Transistors c. Diodes 148. What is the mathematical relation between the electrical resistance (R) in a semiconductor and the temperature (T)? a. Linear (as T increases, R decreases with constant rate) b. Proportional (as T increases, R increases with constant rate) c. Exponential decay (as T increases, R decreases with increasing rate) 149. What is the mathematical relationship between the generated voltage in a photodiode and the distance from the light source? a. Quadratic (voltage increase as the square of the distance) b. Inversely proportional (decreases as one over the distance) c. Exponential (increases with increasing rate) 150. Which of the following statements is true about the element Germanium? a. The resistivity at room temperature is lower than that of Copper b. When heated the resistivity decreases c. The resistivity is constant over a wide range 151. The most common material in modern integrated circuits is: a. Silicon b. Carbon c. Titanium  Practical № 7 Date: Signature: Rectifiers. Determination of the parameters of low frequency alternating current pulses. 152. Consider the alternating current (Fig. 3). What fraction of its period (T) does it take to reach from zero to half of its amplitude?(hint: sin300=1/2) a. 1/6 T b. 1/12 T c. 1/8 T Figure 3 153. What particles are the electric current carriers (charge carriers) in metals? a. Electrons b. Ions c. Electrons and holes 154. For the photoelectric effect to take place, the wavelength (λ) of the incident light must satisfy the following inequality: a. λ ≥ ɸ/h Where: ɸ is the minimum energy needed to remove an electron b. λ ≤ hc/ ɸ c. λ ≥ c/ɸ from metal (work function); h is Plank constant. 155. Electric current is measured in units of amps (A) which represent the following rate of change: a. Charge per time, Q/t b. Energy per charge, E/Q c. Energy per distance, E/x 156. Alternating current (AC): a. Changes frequency with time b. Changes power with time c. Changes direction with time 157. The Oscilloscope measures and displays the relationship between two variables, input (y- axis) andreference (x-axis). Choose the correct pair: a. Time (input) vs Voltage (reference) b. Voltage (input) vs Time (reference) c. Current (input) vs Voltage (reference) 158. The current carriers inside vacuum tubes are: a. Electrons b. Ions c. Electrons and holes 159. The term ”charge carrier” refers to: a. Strictly to electrons and holes b. Strictly to electrons and protons c. Any particle that has an electric charge 160. The term ”elementary charge“ refers to: a. The charge of the electron b. The charge of any charge carrier c. The charge of any elementary particle 161. If across 25Ohm resistor is applied 50V (DC) how many Amperes is the current that will flow: a. 20 mA b. 0.5 A c. 2 A 162. What happens to the current (DC) in metallic conductor, if the voltage is doubled? a. It will be halved b. It will double c. It will stay the same 163. Ohm’s Law states that the magnitude of the electric current is proportional to the applied voltage and inversely proportional to the resistance in the conducting material. Choose one: a. I = V/R b. I = R/V c. I =V·R 164. For Ohmic load in a DC circuit, what would be the change in power consumption if the voltage is halved?(hint: in Ohmic circuits the ratio V/I = constant, and power = V·I) a. It will double b. It will be halved c. It will be quartered 165. What is the resistance in a load if, when 120 V are applied, it draws a current of 20 Amps: a. 6 Ohms b. 60 Ohms c. 100 Ohms 166. Metals are good conductors of electricity because: a. There are free electrons b. There are free electrons and protons c. There are electrons and positrons 167. A 400 Ohm resistor draws 0.05 A direct current. What is the voltage across the resistor? a. 2 V b. 20 V c. 200 V  Practical № 8 Date: Signature: Generators of high frequency electromagnetic waves. Frequency ranges used in physiotherapy. Inductive and capacitive methods. Determination of the power of electromagnetic wave sources. Safety technique. 168. Which of the following human organs and tissues have the least thermal conductivity? a. Muscles b. Brain c. Skin and fat 169. Which of the following diagnostic/therapeutic methods cause deep tissue heating? a. Thermography b. High frequency electric current therapy c. Deep x-ray therapy 170. Faradization is a method for: a. Electro-stimulation with low frequency pulsed current b. High frequency electromagnetic therapy c. Interferential current therapy of deep-seated tissue 171. The most common frequency used in high-frequency electro-stimulation is: a. 20 Hz b. 20 kHz c. 2 MHz 172. Modern electromyography methods rely on the following parameter (chose one): a. Rheobase b. Chronaxie c. Accommodation coefficient 173. Thermography is a medical imaging method that: a. Is harmless b. Has high resolution c. With diagnostic significance similar to MRI 174. Which of the following body fluids and tissues has the least electrical conductivity? a. Blood b. Bones c. Bone marrow 175. Electric resistance (R) is inversely proportional to: a. Electric conductance (G) b. Frequency (f) c. Period (T) 176. What is the main effect that causes heating in microwave diathermy, and also in the microwave oven (f = 2.45 GHz)? a. Resonance: water molecules oscillate with the same frequency b. Dielectric heating: electric dipoles of water are made to rotate c. Refraction: bending of waves inside the substance 177. Electric potential difference is measured in units of volts (V) that represent the ratio of: a. Charge per time, Q/t b. Energy per charge, E/Q c. Energy per distance, E/x 178. Which of following electric currents is the most dangerous for the human body? a. High frequency AC b. Low frequency AC c. Pulsed current 179. Which of the following currents will cause stimulation in excitable tissue (nerves or muscles)? a. Low frequency, pulsed, above threshold b. Low frequency, alternating, below threshold c. High frequency, alternating, above threshold 180. High-frequency generators produce electromagnetic waves with: a. Aperiodic behavior b. Constant amplitude c. Gradually damping amplitude 181. Which of the following currents causes differential heating in tissues? a. Pulsed current b. High frequency current c. DC current 182. Which of the following features are common forelectrosurgery and electrostimulation? a. The frequency b. The shape of the electrodes c. The use of alternating current 183. Specific heat capacity is defined as: a. The amount of heat needed to raise the temperature of 1 kg of substance by 1 degree Kelvin (or Celsius) b. The heat released during the controlled burn of 1 kg of substance c. The heat gain in a substance when Gibbs free energy increases by 1 joule 184. Electrosurgical procedures apply alternating current in the radio frequency (RF) range (100 kHz - 5 MHz) directly to the tissue. Why during electrosurgery there is no nerve and muscular stimulations? a. High frequencies currents do not penetrate deep enough b. Oscillations are much faster than membrane depolarization time c. The power is below stimulation threshold 185. What is the heating mechanism of high frequency alternating current (2MHz)? a. Brief polarization of tissue b. Oscillations of ionized molecules, rotation of dipoles and associated collisions c. Absorption of energy from the electromagnetic waves 186. When an inductor (L) and a capacitor (C) are connected in series, the resulting (L-C) electric circuit is called: a. Operational amplifier (compares and amplifies signal) b. Current rectifier (converts AC into DC) c. Harmonic oscillator (used to emit radio waves) 187. The Earth surface is (reasonably) constant potential reference, and for that reason taken to be the : a. Infinite potential b. Negative potential c. Zero potential  Practical № 9 Date: Signature: Calculation of magnification and resolution of an optical microscope and choice of observation technique. 188. To get a good quality image when using anoptical microscope, the object must be placed at a distance: a. Less than the focal distance of the objective b. Greater than one focal distance but less than double the focal distance of the objective c. Exactly at the focal distance 189. The magnification of the objective is: a. Linear b. Angular c. Both, linear and angular 190. The optimal combination of objective and ocular (eye piece) in an optical microscope requires the following relationship between the respective magnification coefficients (W): a. Wocl = Wobj b. Wocl>Wobj c. Woclp+)to conserve charge, energy, and other physical quantities c. There are certain amount of electrons in the nucleus, which are release during nuclear transmutation 347. Isotopes are: a. Atoms with the same number of protons but different number of neutrons b. Atoms with the same mass numbers (n+p) but different numbers of protons c. Atoms with the same number of protons but different number of electrons 348. The nuclear force (strong force) is one of four known fundamental forces that: a. Keeps the electrons near the nucleus b. Causes Beta decay when there are too many protons or neutrons c. Keeps protons and neutrons bound together 349. Neutrinos are light, weakly-interacting, elementary particles produced during: a. Alpha decay b. Beta decay c. Isomeric transitions (delayed gamma decay) 350. The nuclear force is? a. Strong, long range, attractive b. Weak, short range, repulsive c. Strong, short range, attractive 351. The “mass defect” is also known as: a. Binding energy b. Work function c. Rest mass 352. The relationship between Half-life (T1/2) and the decay constant (λ) is: a. T1/2 = ln(2)·λ b. T1/2 = ln(2)/λ c. T1/2 = ln(2) + λ 353. Electron binding energy (work function) is: a. The energy required to move an electron from lower orbit to higher orbit (excited state) b. The energy required to move an electron from higher orbit into lower atomic orbit (ground state) c. The energy required to completely free the electron from atomic bondage 354. What is the resulting element after Alpha decay of: ? a. b. c. 355. What is the resulting element after Beta minus decay of: ? a. b. c. 356. When a gamma ray is emitted from the nucleus, there is a decrease in the: a. Charge of the nucleus b. Mass number c. Energy of the nucleus 357. Alpha particles are composed of: a. Two protons and two neutrons b. Hydrogen nuclei c. Two protons and two electrons 358. The Atomic Number of an element is equal to the: a. Number of neutrons in the nucleus b. The sum of the protons and neutrons c. The number of protons in the nucleus 359. Isotopes of the same element differ by the: a. Number of protons in the nucleus b. Number of electrons in the atom c. Number of neutrons in the nucleus 360. Which of the following types of ionizing radiation can be stopped by few millimeters of paper? a. Alpha particles b. Beta particles c. Gamma rays 361. Which radiation sources can be contained safely in aluminum container with wall thickness 7-8 mm? a. Alpha and Beta sources b. Alpha and Gamma sources c. Beta and Gamma sources 362. Which type of radiation rays has the highest penetration depth (and lowest attenuation coefficient)? a. Alpha b. Beta c. Gamma 363. What is the (atomic) mass number of an element? a. The average mass of its isotopes b. The mass of the nucleus c. The total number of nucleons (p+n) 364. What happens when an electron collides with a positron? a. Annihilation and gamma emission b. Compton scattering c. Creation of proton and anti-neutrino 365. If a nucleus undergoes Alpha and then Beta minus (β-)decays, the total charge of the nucleus will (where q is the elementary charge): a. Decrease by 1q b. Decrease by 2q c. Decrease by 3q Practical №13 Date: Signature: 99m Obtaining the energy spectrum of the radionuclide Tc and determination of the position and width of the energy “window” of the installation for radionuclide diagnostics 366. Which of the following atomic/molecular energy transitions does NOT produce Gamma radiation? a. Electron orbital transitions b. Nuclear de-excitation c. Nuclear fission 367. The energy of the gamma-photon used in medical diagnostic equipment, must be such that it: a. Moves across the body (of the patient) and triggers an event in the scintillation detector b. Moves across the body of the patient without attenuation c. Moves across the body of the patient without damaging healthy tissue 368. The photomultiplier tube in a gamma-detector system is used for: a. Generation of photons (scintillation) b. Filtering the excess gamma radiation c. Generation of electrons and amplification of the signal 369. Order the events in a gamma-camera detector according to their sequence of occurrence: a. Secondary electron emission b. Photoelectric emission …… → …… → …… c. Photoluminescence 370. The scintillation crystal in a gamma-camera has the following properties: a. Absorbs gamma photon and emits visible light b. Absorbs light and emits a gamma photon c. Emits electrons and multiply their numbers 371. Scintillation crystals are used in: a. Doppler ultrasound b. Roentgen tubes (x-ray) c. Gamma-ray detectors 372. Technetium-99m (99mTc) is used for: a. Radio-therapy b. In-vivo diagnostics c. Laser gain medium 373. Positron-Emission Tomography (PET scan) is based on: a. Emission of photons from electron transitions from excited to ground energy states b. Electron-positron pair production near the strong electric field of the nucleus c. Gamma ray emission in two opposite directions from electron-positron annihilation (following a beta plus decay) 374. Magnetic Resonance Imaging (MRI) provides contrast between different soft tissues, based on: a. Attenuation of the propagating through the tissue radiowaves (RF) b. The difference in the density (ρ) of the tissues c. The relaxation time of exited hydrogen nuclei (protons) 375. Hounsfield unit (HU) is a measure ofx-ray attenuation used in Computed Tomography. The unit scale is recalibrated to set 0 for water.What do you expect to be the HU for bone tissue? a. Near 0 b. -100 c. Greater than 700 376. Hounsfield unit (HU) is a measure of x-ray attenuation used in Computed Tomography. The unit scale is recalibrated to set 0 for water. What do you expect to be the HU for fat tissue? a. Near 0 b. -100 c. 100 377. The term ”proton volume density” applies to image formation in: a. Ultrasound Echography b. Magnetic Resonance Imaging (MRI) c. Positron Emission Tomography (PET) 378. In-vivo radio-diagnostic equipment uses detectors sensitive to this type of ionizing radiation: a. Alpha particles b. Beta particles c. X-ray and gamma photons 379. Magnetic Resonance Imaging (MRI) is based on the following property of the atomic nucleus: a. Radioactivity b. Electric charge c. Magnetic moment 380. Computed tomography (CT scan) is based on: a. Multiple x-rays taken from different directions b. The magnetic resonance of Hydrogen nuclei c. Electron-positron pair production 381. Longitudinal time of relaxation (T1) is term used in: a. PET scan b. Ultrasound Doppler c. MRI 382. When a crystal of Sodium Iodate NaI (Ti) is exposed to gamma radiation, it will emit: a. Electrons b. Positrons c. Visible light 383. When trying to group gamma photons according to their energy distribution, the detector should be switched in: a. Differential mode b. Integral mode c. Integral mode with variable threshold level d. Differential with variable channel bandwidth Practical № 14 Date: Signature: Determination of irradiation during and/or monitoring units in radiation therapy with high energy ionizing radiation 384. In order to reduce the energy of the electrons produced through a photoelectric effect, one needs to: a. Increase the intensity of the incident light beam b. Increase the wavelength of the incident light beam c. Increase the frequency of the incident light beam 385. During cancer radiation therapy, the malignant tissue is affected by: a. Generation of excess heat b. Ionization of tissues c. Generation of (non-native) toxins 386. Which of the following conditions is associated with radioactivity? a. Accelerated electron beams b. X-rays beams c. Unstable nuclides 387. Indirect ionizing radiation: a. Have positive charge b. Have negative charge c. Have no electric charge 388. Which of the three basic interaction modes, between radiation and matter, dominates during medical treatment with 60Co gamma rays (refer to Fig. 6)? a. Photoelectric absorption b. Compton effect (scattering) c. Pair production (electron-positron) Figure 6 389. Compton effect (scattering) is the predominant mode of interaction between radiation and tissue (mostly water) for the following energy range: a. 60 keV – 10 MeV b. 0.5 MeV – 5 MeV c. Up to 460 keV 390. The unit Absorbed Dose of ionizing radiation is called “Gray” (Gy), and measures the amount of energy absorbed per unit mass. Choose the correct units: a. Gy = C/kg b. Gy = J/Kg·s c. Gy = J/Kg 391. What property of Gamma-rays makes them more appropriate for treatment of deep- seated tumors? a. The maximum dose is not near the surface but deep within the body b. The absorbed dose decreases gradually within the body c. The absorbed dose falls rapidly within the body 392. What property of Electron beams, produced in medical accelerators, make them better suited for treatment of surface and skin tumors (see Fig. 7)? a. The maximum electron energy is lower than the maximum photon energy b. The absorbed dose drops gradually with penetration depth c. The absorbed dose drops rapidly with penetration depth  Figure 7 393. The unit Gray (Gy) measures: a. Absorbed dose b. Exposure c. Activity 394. The unit Sievert (Sv) is the product of absorbed dose and radiation weighting factor (wR), specific for different types of tissue. It measures a quantity called: a. Equivalent dose b. Absorbed dose c. Dose rate 395. In medical radiology the unit of Exposure (X) measures how much electric charge is produced by ionization per unit mass. Choose the correct units: a. J/Kg b. C/kg c. C/s 396. Directly ionizing radiation is composed of: a. Charged particles b. Electromagnetic waves c. Neutrinos 397. Which of the following processes produces scattered photons? a. Electron –Positron pair production b. Compton effect c. Piezoelectric effect 398. Probability for Compton scattering (linear attenuation coefficient) depends strongly on: a. Atomic number b. Electron density per unit mass c. Atomic mass number 399. In a photoelectric event, the incident photon: a. Loses all of its energy b. Loses fraction of its energy c. Does not lose energy 400. Coherent scattering (Rayleigh scattering) is when after the collision the incident photon: a. Changes its energy b. Changes its direction and frequency c. Changes direction 401. The Absorbed Dose (D) as well as the Equivalent Dose (H) received during radiotherapy are measured in units of: a. Energy absorbed per unit mass b. Ionization events per unit volume c. Total number of alpha and beta particles imparted on unit surface 402. Absorbed and Equivalent doses will have the same numerical values for this type of ionizing radiation: a. Gamma rays b. Neutrons c. Protons 403. What particles are emitted in a photoelectric effect? a. No particles are emitted, only photons are absorbed b. Electrons c. Photons 404. The Nobel Price for the explanation of the photoelectric effect, was awarded to: a. Isaak Newton b. Michal Faraday c. Albert Einstein 405. Solar panels (photovoltaic cells) are based on this effect: a. Electron-positron pair production b. Photoelectric effect c. Coherent scattering 406. Gas (such as air) can be ionized by: a. Microwaves b. Ultraviolet rays c. Infrared rays 407. For external radiotherapy, medical accelerators, and cobalt-60 units are used. With respect to radiation safety, what is the most significant difference between the two? a. Accelerators generate higher energy radiation; b. Cobalt-60 emits higher energy photons; c. Accelerators produce radiation only when powered on, and cobalt-60 sources are always on (produce radiation continuously).