What is a nucleonic sensing method employing usually one or more radioisotope sources and radiation detectors? A. Radiation sensing B. Sonic level sensing C. Conductivity level sensing D. Dielectric variation sensing 2. What is concerned with the measurement of electric signals on the scalp with arise from the underlying neural activity in the brain (including synaptic sources)? A. ECG B. EEG C. Ultrasound D. EKG 3. In therapeutic radiology and in nuclear medicine, the energies of interest range from about A. 10 to 100 KeV B. 100 to 10000 KeV C. 10000 to 10000 KeV D. 1 to 10 KeV 4. Which of the following is a four-layer diode with an anode gate and a cathode gate? A. SCS B. SCR C. SBS D. SUS 5. What is basically a two-terminal parallel-inverse combination of semiconductor layers that permits triggering in either direction? A. Diac B. Triac C. Quadrac D. Shockley Diode 6. What is the typical value of the interbase resistance of UJTs? A. 20 KΩ B. Between 4 to 4 KΩ C. 4 KΩ D. Between 4 to 10 KΩ 7. PUT stands for A. Programmable Unijunction Transistor B. Programmable Universal Transistor C. Pulse Unijunction Transistor D. Pulse Universal Transistor 8. Which transistor conducts current in both directions when turned on? A. Diac B. SCR C. Quadrac D. SCS 9. What is a three terminal device used to control large current to a load? A. SCR B. SCS C. GTO D. Thyristor
10. What is the other term for thermoelectric effect? A. Seebeck effect B. Hall effect C. Photoelectric effect D. Thermal effect 11. What are the regions corresponding to open-circuit condition for the controlled rectifier which block the flow of charge from anode to cathode? A. Forward blocking regions B. Reverse blocking regions C. Breakdown regions D. Both A and B above 12. The V-I characteristics for a triac in the first and third quadrants are essentially identical to those of _____ in the quotation. A. SCR B. UJT C. Transistor D. SCS 13. When the temperature increases, the inter-base resistance of a UJT A. Remains unchanged B. Increases C. Decreases D. is zero 14. The three terminals of a triac are A. drain, source, gate B. two main terminals and a gate terminal C. cathode, anode and gate D. anode, source, gate 15. A triac is equivalent to two SCRs A. in parallel B. in inverse-parallel C. in series D. in inverse-series 16. In diagnostic radiology and for superficial therapy purposes, the energy spectrum of radiation varies from about A. 1 to 10 KeV B. 10 to 100 KeV C. 100 to 10000 KeV D. 10000 to 100000 KeV 17. The x-ray region of the electromagnetic spectrum has a corresponding range of wavelengths from A. 0.1 to 0.0001 nm B. 0.1 to 0.0001 pm C. 0.1 to 0.0001 μm D. 0.1 to 0.0001 mm 18. The three terminals of an SCR are the A. anode, cathode, and grid B. cathode, anode, gate C. anode, cathode, drain D. drain, source, gate 19. If a body is considered as a conducting sphere of 0.5m radius its capacitance to infinity is A. 55 pF B. 55 nF C. 55 μF
D. 55 F 20. How many semiconductor layers does an SCR have? A. Four B. Two C. Three D. Five 21. A triac is a _____ switch. A. unidirectional B. mechanical C. bidirectional D. omnidirectional 22. Which of the following is the normal way to turn on an SCR? A. By breakover voltage B. By appropriate anode current C. By appropriate cathode current D. By appropriate gate current 23. A triac can pass a portion of _____ half cycle through the load A. only positive B. only negative C. both positive and negative D. neither positive nor negative 24. A diac has how many terminals? A. Two B. Three C. Four D. Five 25. An SCR combines the feature of A. a rectifier and resistance B. a rectifier and capacitor C. a rectifier and transistor D. a rectifier and inductor 26. Which is the control element in an SCR? A. Anode B. Cathode C. Gate D. Cathode supply 27. How many semiconductor layers does a triac have? A. Two B. Four C. Three D. One 28. A diac has how many semiconductor layers? A. Three B. Four C. Two D. Five 29. The p-type emitter of a UJT is _____ doped. A. lightly B. moderately C. heavily D. not 30. A diac has
A. one pn junction B. three pn junctions C. two pn junctions D. four pn junctions 31. A UJT is sometimes called a ____ diode. A. double-based B. single-based C. a rectifier D. a switching diode 32. A diac is _____ switch. A. an AC B. a mechanical C. a dc D. both ac and dc 33. An SCR is made of silicon and not germanium because silicon. A. is inexpensive B. has low leakage current C. is mechanically strong D. is tetravalent 34. What is the control element in an SCR? A. Gate B. Anode C. Grid D. Cathode 35. An effect that reduces the possibility of accidental triggering of the SCS. A. Miller effect B. Rate effect C. End effect D. Flywheel effect 36. Which of the following is a common application of UJT? A. Amplifier B. Rectifier C. Mulitivibrator D. Sawtooth generator 37. Which device does not have a gate terminal? A. Triac B. SCR C. FET D. Diac 38. An SCR is a _____ triggered device. A. current B. power C. voltage D. noise 39. When UJTs is turned on, the resistance between emitter terminal and lower base terminal A. remains unchanged B. increases C. decreases D. becomes zero 40. The UJT has A. two pn junctions B. three pn junctions C. one pn junction D. four on junction 41. The UJT may be used as A. an amplifier B. a rectifier C. a sawtooth generator D. a multivibrator 42. Which of the following is the normal
way to turn on a diac? A. By breakover voltage B. By gate voltage C. By gate current D. By anode current 43. Power electronics deals with the control of ac power at what frequencies essentially? A. 20 KHz B. 1000 KHz C. Frequencies less than 10 Hz D. 60 Hz frequency 44. When the emitter terminal of a UJT is open, the resistance between the baseterminals is generally A. low B. extremely low C. high D. extremely high 45. AC power in a load can be controlled by connecting A. two SCRs in series B. two SCRs in parallel C. two SCRs in parallel opposition D. two SCRs in series opposition 46. Which equation defines the intrinsic stand off ratio (η) of UJTs? A. R B1 / (R B1 + R B2 ) B. (R B1 + R B2 ) / R B1 C. (R B1 + R B2 ) / R B2 D. R B1 + R B2 47. To turn off the SCR, which of the following is done? A. Reduce gate voltage to zero B. Reverse bias the gate C. Reduce anode voltage to zero D. Reduce cathode voltage to zero 48. Control system that maintains a speed voltage, or other variable within specified limits of a preset level. A. Controller B. Regulator C. Sensor D. Computer 49. To turn on the UJT, the forward bias on emitter diode should be _____ the peak point voltage. A. more than B. less than C. equal to D. twice 50. When the temperature increases, the intrinsic stand off ratio A. increases B. decreases C. essentially constant D. becomes zero 51. What is dimensionless parameter of the second-order characteristic equation? A. Damping ratio B. Accuracy
C. Efficiency ratio D. Transfer function ratio 52. What is the ratio of two exponential functions of time called? A. Transfer function B. Damping ratio C. Efficiency D. Gain 53. A diac is turned on by A. breakover voltage B. gate current C. gate voltage D. anode current 54. An SCR whose state is controlled by the light falling upon a silicon semiconductor layer of the device. A. SCS B. GTO C. Thyristor D. LASCR 55. A diac is simply A. a single junction B. a three junction device C. a triac without a gate terminal D. the SCR 56. What region lies between the peak point and valley point of UJT emitter characteristic? A. Saturation B. Cut off C. Negative resistance D. Positive resistance 57. What refers to the application of electronic theory, technology, instrumentation, and computing system to biological research and medical problems? A. Medical electronics B. Genetics electronics C. Biomedical engineering D. Biomedical electronics 58. Which device exhibits negative resistance region? A. Diac B. Triac C. Transistor D. UJT 59. The UJT operates in what region after peak point? A. Cut off B. Negative resistance C. Saturation D. Positive resistance 60. SCR is a rectifier constructed of silicon material. Silicon is chosen because A. it is the most abundant material B. of its strength and
