1. An SCR is a solid state equivalent of a _____.

Answers:

  1. triode
  2. pentode
  3. thyratron
  4. diode

2. If the input to an integrating circuit is a square wave, the output will be _____.

Answers:

  1. triangular
  2. rectangular
  3. saw-tooth
  4. spiked

3. A P-type material is _____.

Answers:

  1. positively charged
  2. negatively charged
  3. electrically neutral
  4. none of the above

4. The stability factor of a biasing circuit is 10. What does it mean?

Answers:

  1. Ic changes 10 times as munch as any change in Ico(leakage current)
  2. Ib changes 10 times as much as any change in Ico
  3. Ie change 10 times as munch as any change in Ico

5. According to the Barkhausen criterion for oscillators_______.

A – open loop gain
ß – feed back factor

Answers:

  1. Aß < 1
  2. Aß > 1
  3. Aß = 1
  4. Aß = 1

6. If the reverse bias on the gate of an FET is increased , the width of the conducting channel will _____.

Answers:

  1. increase
  2. decrease
  3. remain constant

7. An FET has the following parameters IDSS = 32mA , VGS ( off ) = -8V , VGS = -4.5V. What will be the drain current?

Answers:

  1. 5.2 mA
  2. 6.12 mA
  3. 7.03 mA
  4. 7.45 mA

8. For good stabilization of the operating point in a voltage divider bias, the current I, flowing through potential dividers R1 and R2, should be equal to or greater than _____.
(IB-base current)

Answers:

  1. 2IB
  2. 10IB
  3. 4IB
  4. IB/2

9. If in a transistor IE = 10.5mA , IC = 10mA,the value of ß will be _____.

Answers:

  1. 0.2
  2. 200
  3. 100
  4. 20

10. The slope of the D.C load line of a transistor circuit having a collector load Rc is _____.

Answers:

  1. Rc
  2. 1/Rc
  3. -1/Rc
  4. 2Rc

11. Tuning is generally accomplished by varying _____.

Answers:

  1. L(inductor)
  2. C(capacitor)
  3. both L and C
  4. R(resistor)

12. A triac can pass a portion of _____.

Answers:

  1. positive half-cycle through the load
  2. negative half-cycle through the load
  3. both positive and negative half-cycles through the load
  4. None of the above

13. An A.C supply of 230v is applied to a half wave rectifier circuit through a transformer of turn ratio 10:1. Its D.C voltage output will be _____.

Answers:

  1. 5v
  2. 12v
  3. 10.36v
  4. 5.18v

14. A vacuum tube conducts current _____.

Answers:

  1. from the cathode to the anode
  2. from the anode to the cathode
  3. in both the above directions
  4. alternately in both directions

15. If a circuit of full-wave centre-tapped rectifier with capacitor filter employs a load RL = 100O, and C = 1050µF and the frequency is 50HZ , what would be the ripple factor?

Answers:

  1. 40%
  2. 30%
  3. 22%
  4. 27%

16. Two identical germanium diodes are connected in series opposition. A 10V battery is impressed upon this series arrangement. What will be the voltage across each diode room temperature if the Zener breakdown voltage of each diode is 9.8V?

Answers:

  1. VD1= 0.2V , VD2 = 9.8V
  2. VD1 = 10V , VD2 = 0V
  3. VD1 = 0V , VD2 = 10V
  4. VD1 = 9.8V , VD2 = 0.2V

17. A varactor diode can function as a variable capacitor with a________ forward bias.

Answers:

  1. very slight
  2. moderate
  3. heavy

18. Radio frequencies have their range above _____.

Answers:

  1. 20KHZ
  2. 50KHZ
  3. 100KHZ
  4. 200KHZ

19. Tuned amplifiers are generally operated as

Answers:

  1. class A amplifiers
  2. class B amplifiers
  3. class AB amplifiers
  4. class C amplifiesrs

20. In the collector feedback biasing, ß = 57 , RC = 1 kO , IB = 60µA and VCB = 4.5V. The value of the stability factor will be _____.

Answers:

  1. 30.4
  2. 32.9
  3. 57
  4. 4.5

21. In the enhancement mode (MOSFET) , conductivity increases _____.

Answers:

  1. with the decrease in positive gate voltage
  2. with the increase in positive gate voltage
  3. with the decrease in negative gate voltage
  4. with the increase in negative gate voltage

22. A three-stage amplifier has a first-stage voltage gain of 100, a second stage voltage gain of 200 and a third stage gain of 400. The total voltage gain in db will be _____.

Answers:

  1. 130 dB
  2. 140 dB
  3. 132 dB
  4. 138 dB

23. The output characteristics of an FET closely resemble the plate characteristics of a________ valve.

Answers:

  1. diode
  2. triode
  3. tetrode
  4. pentode

24. The Q-factor of a parallel tuned circuit is given by _____.

Answers:

  1. 1/RvC/L
  2. RvL/C
  3. 1/RvL/C
  4. RvC/L

25. At parallel resonance, a tuned circuit offers an impedance of _____.

Answers:

  1. C/LR
  2. R/LC
  3. L/CR
  4. 2L/CR

26. When a transistor has to act as a switch, it must operate in _____.

Answers:

  1. the active region
  2. the cut-off region
  3. the saturation region
  4. both the cut off and the saturation regions

27. The V-I characteristics of a triac in the first and third quadrants are essentially identical to those of _______ in the first quadrant

Answers:

  1. a transistor
  2. a UJT
  3. a zener diode
  4. an SCR

28. In the d.c. equivalent circuit of a transistor amplifier , the capacitors are regarded as _____.

Answers:

  1. Open
  2. Short
  3. Sometimes open and sometimes short
  4. Unchanged

29. The output frequency of a half-wave rectifier is _____.

Answers:

  1. double the input A.C frequency
  2. half the input A.C frequency
  3. equal to the input A.C frequency
  4. None of the above

30. The maximum efficiency of a full wave rectifier is _____.

Answers:

  1. 40%
  2. 81.2%
  3. 90%
  4. 99%

31. If the collector supply voltage is 10v, the collector cut off voltage under D.C conditions will be _____.

Answers:

  1. 5v
  2. 10v
  3. 20v
  4. 30v

32. The relationship among bandwidth, resonant frequency and Q of a tuned circuit is _____.

Answers:

  1. BW = Q/fr
  2. BW = Q fr
  3. BW = frvQ
  4. BW = fr/Q

33. Why is the control grid of a tube always held at negative potential W.R.T cathode.?

Answers:

  1. in order to avoid heating of the tube
  2. in order to obtain faithful amplification
  3. in order to set its operating point
  4. None of the above

34. If in a transistor , Ic = 9.5mA , Ie = 10mA , the value of a will be _____.

Answers:

  1. 0.95
  2. 10
  3. 9.5
  4. 0.095

35. In an R-C phase shift oscillator, an R-C network is designed to introduce a phase shift of _____ .

Answers:

  1. 300
  2. 600
  3. 900
  4. 1800

36. If the input to a differentiating circuit is a square wave, the output will be _____.

Answers:

  1. rectangular
  2. spiked
  3. triangular
  4. sinusoidal

37. For faithful amplification, VBE must not fall below _____.

Answers:

  1. 0.9v for si transistors
  2. 0.5v for si transistors
  3. 0.3v for si transistors
  4. 0.7v for si transistors

38. Tuned amplifiers are used for the amplification of _____.

Answers:

  1. audio frequencies
  2. RF
  3. very low frequencies
  4. very high frequencies

39. For an R-C phase shift oscillator , the frequency of oscillation will be given as _____.

Answers:

  1. fo = 1/2?vRC
  2. fo = 1/2?v6RC
  3. fo = 1/v2?RC
  4. fo = 2/v2?RC

40. A reversed biased P-N junction has a resistance of the order of _____.

Answers:

  1. O
  2. KO
  3. MO
  4. mO

41. The impedance of a parallel tuned circuit at resonance is _____.

Answers:

  1. 0
  2. low
  3. very high
  4. very low

42. A transistor amplifier has 4v,2mA as the operating point. For faithful amplification, the collector current due to signal alone should not exceed _____.

Answers:

  1. 2mA
  2. 1mA
  3. 4mA
  4. 8mA

43. A D.C milliammeter connected to a half-wave rectifier supplying a maximum current of 10mA will read _____.

Answers:

  1. 10 mA
  2. 20 mA
  3. 5 mA
  4. 3.18 mA

44. An SCR combines the features of_____.

Answers:

  1. a rectifier and an amplifier
  2. a rectifier and a transistor
  3. a rectifier and an oscillator
  4. a rectifier and an inverter

45. Hartley oscillator is _____.

Answers:

  1. an RC oscillator
  2. an LC oscillator
  3. a Crystal oscillator

46. If in a transistor VCB= 4V , VBE = 0.7V, the VCE will be equal to _____.

Answers:

  1. 4.7v
  2. 5.4v
  3. 3.3v
  4. 0.7v

47. Vacuum tubes are _____.

Answers:

  1. linear devices
  2. non-linear devices
  3. both linear and non-linear under different conditions

 

48. The input and output voltages of a CE transistor amplifier are _____.

Answers:

  1. in phase
  2. 90° out of phase
  3. 180° out of phase
  4. 120° out of phase

49. An FET has ________ temperature co-efficient of resistance.

Answers:

  1. 0
  2. positive
  3. negative

50. An :FET is a _____.

Answers:

  1. bipolar device
  2. tripolar device
  3. unipolar device

51. The complementary MOS(CMOS) uses _____.

Answers:

  1. only n-channel devices in the circuit
  2. only p- channel devices in the circuit
  3. both n and p channel devices in the circuit
  4. None of the above

52. When a transistor is driven to saturation, ideally, the Vce is _____.

Answers:

  1. VCC
  2. VCC/2
  3. 0
  4. 2VCC

53. A 3-ohm load is coupled to a transistor amplifier through a step-down transformer. If the D.C resistance of the primary winding is 300O and the output resistance of the amplifier is 3KO, what should be the turn ratio for the transfer of maximum power?

Answers:

  1. Np/Ns=40
  2. Np/Ns=20
  3. Np/Ns=30
  4. Np/Ns=10

54. The ideal value of the stability factor is _____.

Answers:

  1. 0
  2. 10
  3. 1
  4. 100

55. If the A.C input to a half-wave rectifier has an R.M.S valve of 400/v2 v, the peak inverse voltage will be _____.

Answers:

  1. 400 v
  2. 400v2 v
  3. 800v2 v
  4. 800/v2 v

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