Analog Electronics

41. The encapsulation of transistor is necessary for

  1. preventing radio interference
  2. preventing photo-emission effects
  3. avoiding loss of free electrons
  4. mechanical ruggedness

Correct answer: (D)
mechanical ruggedness

42. In a transistor leakage current mainly depends on

  1. doping of base
  2. size of emitter
  3. rating of transistor
  4. temperature

Correct answer: (D)
temperature

43. In a CB amplifier the maximum efficiency could be

  1. 99%
  2. 85%
  3. 50%
  4. 25%

Correct answer: (D)
25%

44. When a transistor is connected in common emitter mode, it with have

  1. negligible input resistance and high output resistance
  2. high input resistance and low output resistance
  3. medium input resistance and high output resistance
  4. low input resistance as well as output resistance

Correct answer: (C)
medium input resistance and high output resistance

45. In all base driver amplifiers

  1. ac collector voltage is 180° out of phase with ac base voltage
  2. ac emitter voltage is 180° out of phase with ac base voltage
  3. ac collector voltage is in phase with ac base voltage
  4. none of the above

Correct answer: (A)
ac collector voltage is 180° out of phase with ac base voltage

46. The horizontal intercept of dc load line is the same as ideal

  1. cut off point
  2. saturation point
  3. operating point
  4. quasi saturation point

Correct answer: (A)
cut off point

47. In deriving ac equivalent circuit for an amplifier circuit we short circuit

  1. all resistors
  2. all transistors
  3. all inductors
  4. all capacitors

Correct answer: (D)
all capacitors

48. Which of the following statements is false?

  1. Push pull signals are equal and opposite in phase
  2. Class AB operation cannot be used for a push pull audio power output phase
  3. A push pull output transformer has a centre-tapped primary
  4. All of the above

Correct answer: (B)
Class AB operation cannot be used for a push pull audio power output phase

49. Which of the following amplifier circuit using junction transistor has the best gain?

  1. Common base
  2. Common emitter
  3. Common collector
  4. All have the same gain

Correct answer: (B)
Common emitter

50. In an op-amp differentiator

  1. the amplitude of output is proportional to rate of change of input
  2. the amplitude of output is proportional to input
  3. output occurs when input is finite and constant
  4. polarity of input and output is the same

Correct answer: (A)
the amplitude of output is proportional to rate of change of input

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