Multiple Choice Questions Topic Outline
- MCQs in Industrial Electronics
- MCQs in Electronic Control System
- MCQs in Industrial Solid State Services
- MCQs in Welding Systems
- MCQs in Thyristors
- MCQs in High Frequency Heating
- MCQs in Feedback Systems / Servomechanism
- MCQs in Transducers
- MCQs in Motor Speed Control Systems
- MCQs in Robotic Principles
- MCQs in Bioelectrical Principles
- MCQs in Instrumentation and Control
The Series
Following is the list of multiple choice questions in this brand new series:
Start Practice Exam Test Questions Part 1 of the Series
1. 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 base-terminals 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. RB1 / (RB1 + RB2)
- B. (RB1 + RB2) / RB1
- C. (RB1 + RB2) / RB2
- D. RB1 + RB2
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
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