In this article, we published the 100 industrial electronics objective and answers for electrical and instrumentation engineers.
Industrial Electronics Objective Questions
The below list provides all the multiple-choice questions (MCQ) related to industrial electronics.
Answers are available at the bottom of the article.
1. Control system that maintains a speed voltage, or other variables within specified limits of a preset level.
2. An SCR combines the feature of
|A)||a rectifier and transistor|
|B)||a rectifier and resistance|
|C)||a rectifier and inductor|
|D)||a rectifier and capacitor|
3. Which transistor conducts current in both directions when turned on?
4. A normally operated SCR has an anode which is ______ with respect to cathode.
|A)||at zero potential|
|C)||at infinite potential|
5. When the temperature increases, the inter-base resistance of a UJT
6. The triac is fundamentally a/an ______ with a gate terminal for controlling the turn-on conditions of the bilateral device in either direction.
7. How many semiconductor layers does a triac have?
8. The voltage across an SCR when it is turned on is about
9. AC power in a load can be controlled by connecting
|A)||two SCRs in parallel opposition|
|B)||two SCRs in series opposition|
|C)||two SCRs in parallel|
|D)||two SCRs in series|
10. Which of the following is the normal way to turn on an SCR?
|A)||By appropriate gate current|
|B)||By appropriate cathode current|
|C)||By appropriate anode current|
|D)||By breakover voltage|
11. Which is the control element in an SCR?
12. What is the typical value of the interbase resistance of UJTs?
|C)||Between 4 to 10 KΩ|
|D)||Between 4 to 4 KΩ|
13. What Greek word which means “switch”?
14. A control system in which the output is related to the input by device parameters only.
|B)||Closed-loop control system|
|C)||Open-loop control system|
|D)||Feedback control system|
15. When the emitter terminal of a UJT is open, the resistance between the base-terminals is generally
16. Power electronics deals with the control of ac power at what frequencies essentially?
|A)||60 Hz frequency|
|D)||Frequencies less than 10 Hz|
17. A feedback control system in which the controlled variable is mechanical position.
|B)||Closed-loop feedback control system|
|D)||Open-loop feedback control system|
18. An SCR is made of what material?
19. What is basically a two-terminal parallel-inverse combination of semiconductor layers that permits triggering in either direction?
20. When the temperature increases, the intrinsic stand off ratio
21. Which is equivalent to a zener or avalanche region of the fundamental two-layer semiconductor diode?
|B)||Forward breakdown voltage|
|D)||Reverse breakdown voltage|
22. If a body is considered as a conducting sphere of 0.5m radius its capacitance to infinity is
23. What are some areas where GTO is applicable?
|B)||All of the answers|
24. What refers to the application of electronic theory, technology, instrumentation, and computing system to biological research and medical problems?
25. The three terminals of a triac are
|A)||anode, source, gate|
|B)||two main terminals and a gate terminal|
|C)||drain, source, gate|
|D)||cathode, anode and gate|
26. The UJT may be used as
|A)||a sawtooth generator|
27. What is the ratio of two exponential functions of time called?
28. The three terminals of an SCR are the
|A)||cathode, anode, gate|
|B)||anode, cathode, drain|
|C)||drain, source, gate|
|D)||anode, cathode, and grid|
29. What is the control element in an SCR?
30. ECG stands for electrocardiography while EEG stands for?
31. What are the most widely used altitude and altitude-rate transducers?
32. An SCR is a ______ triggered device.
33. 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|
34. What is that voltage above when the SCR enters the conduction region?
|A)||Forward breakover voltage|
|C)||Reverse breakover voltage|
35. What is that value of current below which the SCR switches from the conduction state to the forward blocking region under stated conditions?
36. Which of the following is a four-layer diode with an anode gate and a cathode gate?
37. An SCR whose state is controlled by the light falling upon a silicon semiconductor layer of the device.
38. SCR is a rectifier constructed of silicon material.
Silicon is chosen because
|A)||of its strength and ruggedness|
|B)||of its high temperature and power capabilities|
|C)||it is much cheaper than any other material|
|D)||it is the most abundant material|
39. What is a nucleonic sensing method employing usually one or more radioisotope sources and radiation detectors?
|A)||Sonic level sensing|
|C)||Dielectric variation sensing|
|D)||Conductivity level sensing|
40. What is the sensing element of the acceleration transducer?
41. An SCR is made of silicon and not germanium because silicon.
|A)||has low leakage current|
|C)||is mechanically strong|
42. When UJTs is turned on, the resistance between emitter terminal and lower base terminal
43. A locus or path of the roots traced out on the s-plane as a parameter is changed.
44. An SCR when turned on has a typical voltage across of
45. When the firing angle of SCR is increased, its output
46. The V-I characteristics for a triac in the first and third quadrants are essentially identical to those of ______ in the quotation.
47. What is one of the most widely used sensing elements particularly for pressure ranges higher than 2 MPa?
48. The gate of an SCR is ______ with respect to its cathode.
|B)||at zero potential|
|C)||at infinite potential|
49. When SCR starts conducting, then ______ losses all control.
50. A diac is simply
|A)||a triac without a gate terminal|
|B)||a single junction|
|C)||a three junction device|
51. How many pn junction does SCRs have?
52. What is dimensionless parameter of the second-order characteristic equation?
|B)||Transfer function ratio|
53. What is a solid state equivalent of a gas filled triode?
54. The UJT operates in what region after peak point?
55. An SCR is a member of what family?
56. A triac can pass a portion of ______ half cycle through the load
|B)||both positive and negative|
|D)||neither positive nor negative|
57. A triac is a _______ switch.
58. Which of the following is the normal way to turn on a diac?
|A)||By gate current|
|B)||By breakover voltage|
|C)||By anode current|
|D)||By gate voltage|
59. An effect that reduces the possibility of accidental triggering of the SCS.
60. Which device exhibits a negative resistance region?
61. What region lies between the peak point and valley point of UJT emitter characteristics?
62. Which of the following is a common application of UJT?
63. A diac is turned on by
64. An SCR is a solid state equivalent of which tube?
65. When the SCR is OFF, the current in the circuit is
|B)||large leakage current|
|D)||small leakage current|
66. What is the other term for thermoelectric effect?
67. Which of the following can change the angle of conduction in SCR?
|A)||Changing anode voltage|
|B)||Changing cathode voltage|
|C)||Changing gate voltage|
|D)||Reverse biasing the gate|
68. The SCR can exercise control over ______ of ac supply.
|A)||both positive and negative half-cycles|
|B)||only negative half-cycle|
|C)||only positive half-cycle|
|D)||positive or negative half-cycle|
69. Which of the following is NOT a method primarily used for density sensing?
70. The typical turn-off time of an SCR is about
|A)||5 to 40 µs|
|B)||1 to 5 µs|
|C)||15 to 25 µs|
|D)||20 to 40 µs|
71. What is the typical turn-on time of an SCR?
72. What device measures humidity directly with a single sensing element?
73. A diac has how many terminals?
74. When an SCR is combined to a switch, it is considered as a ______ switch.
75. A triac is equivalent to two SCRs
76. To turn off the SCR, which of the following is done?
|A)||Reduce gate voltage to zero|
|B)||Reduce anode voltage to zero|
|C)||Reverse bias the gate|
|D)||Reduce cathode voltage to zero|
77. A UJT is sometimes called a _______ diode.
|C)||a switching diode|
78. A transduction principle used primarily in optical sensors.
79. To turn on the UJT, the forward bias on emitter diode should be ______ the peak point voltage.
80. A diac is _______ switch.
|D)||both ac and dc|
81. The step response of a first order systems is given by
|A)||y(t) = A0 + A1es1t + A2es2t + A3es3t|
|B)||y(t) = A0 + A1es1t + A2es2t|
|C)||y(t) = A0 + A1es1t|
|D)||y(t) = A0|
82. A diac has how many semiconductor layers?
83. The p-type emitter of a UJT is ______ doped.
84. Acceleration transducers are also called
85. What is the required gate triggering current of GTO?
86. What sensing element is typically made from a thin-walled tube formed into deep convolutions and sealed at one end, whose displacement can then be made to act on a transduction element?
87. How many semiconductor layers does an SCR have?
88. A diac has
|A)||three pn junctions|
|B)||four pn junctions|
|C)||two pn junctions|
|D)||one pn junction|
89. Which device does not have a gate terminal?
90. What is an automatic speed control device using the centrifugal force on rotating flyweights as the feedback element?
91. Which equation defines the intrinsic stand off ratio of UJTs?
|C)||(RB1+RB2) / RB1|
|D)||(RB1+RB2) / RB2|
92. The supply voltage is generally _______ that of breakover voltage in an SCR.
93. The x-ray region of the electromagnetic spectrum has a corresponding range of wavelengths from
|A)||0.1 to 0.0001 µm|
|B)||0.1 to 0.0001 mm|
|C)||0.1 to 0.0001 nm|
|D)||0.1 to 0.0001 pm|
94. What is a three terminal device used to control large current to a load?
95. The UJT has
|A)||two pn junctions|
|B)||one pn junction|
|C)||four on junction|
|D)||three pn junctions|
96. What are the regions corresponding to open-circuit condition for the controlled rectifier which block the flow of charge from anode to cathode?
|A)||Reverse blocking regions|
|C)||Both Forward blocking regions and Reverse blocking regions|
|D)||Forward blocking regions|
97. PUT stands for
|A)||Programmable Unijunction Transistor|
|B)||Programmable Universal Transistor|
|C)||Pulse Unijunction Transistor|
|D)||Pulse Universal Transistor|
98. 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)?
99. When the supply voltage exceeds the breakover voltage of an SCR, it
|B)||conducts leakage current|
|D)||conducts terminal current|
100. In therapeutic radiology and in nuclear medicine, the energies of interest range from about
|A)||10 to 100 KeV|
|B)||1 to 10 KeV|
|C)||100 to 10000 KeV|
|D)||10000 to 10000 KeV|
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