BJT MCQ

51. The base region of p-n-p transistor is

  1. Very thin and heavily doped with holes
  2. Very thin and heavily doped with electrons
  3. Very thin and lightly doped with holes
  4. Very thin and lightly doped with electrons
Answer
Answer. d

52. One advantage of transformer coupling in a transistor amplifier is that

  1. It provides excellent frequency response
  2. It is simple  and less expensive than others
  3. Low power supply may be used
  4. High efficiency and high power output is obtained
Answer
Answer. d

53. In a junction transistor, the doping level of the collector region is

  1. Higher than emitter region
  2. Lower than base region
  3. In higher  than base region but lower than emitter region
  4. Independent of the doping of base and emitter regions
Answer
Answer. c

54. Let us assume the emitter current of a bipolar transistor is IE. If it is made 2IE, then what could be the possible effect on the voltage across the base-emitter junction?

  1. It increases by about 20mV
  2. It doubles
  3. It halves
  4. It decreases by about 20mV
Answer
Answer. b

55. A transistor is operated as a saturated switch to eliminate

  1. Storage time
  2. Turn-off time
  3. Turn-on time
  4. Delay time
Answer
Answer. d

56. For active region operation of n-p-n transistor

  1. Emitter is positive with respect to base
  2. Emitter is negative with respect to base
  3. Emitter is at the same voltage as base
  4. Base is at the same voltage as collector
Answer
Answer. b

57. In a phototransistor, the photocurrent is generated at

  1. Either of the junctions
  2. Emitter-base junction
  3. Collector-base junction
  4. Both the junctions
Answer
Answer. c

58. When a bipolar transistor in cut off region, both the base-emitter and collector-base junction are

  1. Reverse biased
  2. Forward biased
  3. Not biased
  4. None of these
Answer
Answer. a

59. Which of the following transistor circuits have the lowest gain?

  1. Common base
  2. Common collector
  3. Common emitter
  4. None of the above
Answer
Answer. b

60. For transistor action, which of the following statements is correct?

  1. Base, emitter and collector regions should have the same doping concentrations
  2. The base region must be very thin and lightly doped
  3. The emitter junction is reverse biased and collector junction is forward biased
  4. Both the emitter junctions as well as the collector junction are forward biased.
Answer
Answer. b
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