Electronics Post
Q1. A transistor has …………………
1. one pn junction
2. two pn junctions
3. three pn junctions
4. four pn junctions
Q2. The number of depletion layers in a transistor is …………
1. four
2. three
3. one
4. two
Q3. The base of a transistor is ………….. doped
1. heavily
2. moderately
3. lightly
4. none of the above
Q4. The element that has the biggest size in a transistor is ………………..
1. collector
2. base
3. emitter
4. collector-base-junction
Q5. In a pnp transistor, the current carriers are ………….
1. acceptor ions
2. donor ions
3. free electrons
4. holes
Q6. The collector of a transistor is …………. doped
1. heavily
2. moderately
3. lightly
4. none of the above
Q7. A transistor is a …………… operated device
1. current
2. voltage
3. both voltage and current
4. none of the above
Q8. In a npn transistor, ……………. are the minority carriers
1. free electrons
2. holes
3. donor ions
4. acceptor ions
Q9. The emitter of a transistor is ………………… doped
1. lightly
2. heavily
3. moderately
4. none of the above
Q10. In a transistor, the base current is about ………….. of emitter current
1. 25%
2. 20%
3. 35 %
4. 5%
Q11. At the base-emitter junctions of a transistor, one finds ……………
1. a reverse bias
2. a wide depletion layer
3. low resistance
4. none of the above
Q12. The input impedance of a transistor is ………….
1. high
2. low
3. very high
4. almost zero
Q13. Most of the majority carriers from the emitter ………………..
1. recombine in the base
2. recombine in the emitter
3. pass through the base region to the collector
4. none of the above
Q14. The current IB is …………
1. electron current
2. hole current
3. donor ion current
4. acceptor ion current
Q15. In a transistor ………………..
IC = IE + IB
IB = IC + IE
IE = IC – IB
IE = IC + IB
Q16. The value of α of a transistor is ……….
more than 1
less than 1
1
none of the above
Q17. IC = αIE + ………….
1. IB
2. ICEO
3. ICBO
4. βIB
Q18. The output impedance of a transistor is ……………..
1. high
2. zero
3. low
4. very low
Q19. In a tansistor, IC = 100 mA and IE = 100.2 mA. The value of β is …………
1. 100
2. 50
3. about 1
4. 200
Q20. In a transistor if β = 100 and collector current is 10 mA, then IE is …………
1. 100 mA
2. 100.1 mA
3. 110 mA
4. none of the above
Q21. The relation between β and α is …………..
1. β = 1 / (1 – α )
2. β = (1 – α ) / α
3. β = α / (1 – α )
4. β = α / (1 + α )
Q22. The value of β for a transistor is generally ………………..
1. 1
2. less than 1
3. between 20 and 500
4. above 500
Q23. The most commonly used transistor arrangement is …………… arrangement
1. common emitter
2. common base
3. common collector
4. none of the above
Q24. The input impedance of a transistor connected in …………….. arrangement is the
highest
1. common emitter
2. common collector
3. common base
4. none of the above
Q25. The output impedance of a transistor connected in ……………. arrangement is the
highest
1. common emitter
2. common collector
3. common base
4. none of the above
Q26. The phase difference between the input and output voltages in a common base
arrangement is …………….
1. 180o
2. 90o
3. 270o
4. 0o
Q27. The power gain in a transistor connected in ……………. arrangement is the
highest
1. common emitter
2. common base
3. common collector
4. none of the above
Q28. The phase difference between the input and output voltages of a transistor
connected in common emitter arrangement is ………………
1. 0o
2. 180o
3. 90o
4. 270o
Q29. The voltage gain in a transistor connected in ………………. arrangement is the
highest
1. common base
2. common collector
3. common emitter
4. none of the above
Q30. As the temperature of a transistor goes up, the base-emitter resistance ……………
1. decreases
2. increases
3. remains the same
4. none of the above
Q31. The voltage gain of a transistor connected in common collector arrangement is
………..
1. equal to 1
2. more than 10
3. more than 100
4. less than 1
Q32. The phase difference between the input and output voltages of a transistor
connected in common collector arrangement is ………………
1. 180o
2. 0o
3. 90o
4. 270o
Q33. IC = β IB + ………..
1. ICBO
2. IC
3. ICEO
4. αIE
Q34. IC = [α / (1 – α )] IB + ………….
1. ICEO
2. ICBO
3. IC
4. (1 – α ) IB
Q35. IC = [α / (1 – α )] IB + […….. / (1 – α )]
1. ICBO
2. ICEO
3. IC
4. IE
Q36. BC 147 transistor indicates that it is made of …………..
1. germanium
2. silicon
3. carbon
4. none of the above
Q37. ICEO = (………) ICBO
1. β
2. 1 + α
3. 1 + β
4. none of the above
Q38. A transistor is connected in CB mode. If it is not connected in CE mode with same
bias voltages, the values of IE, IB and IC will …………..
1. remain the same
2. increase
3. decrease
4. none of the above
Q39. If the value of α is 0.9, then value of β is ………..
1. 9
2. 0.9
3. 900
4. 90
Q40. In a transistor, signal is transferred from a …………… circuit
1. high resistance to low resistance
2. low resistance to high resistance
3. high resistance to high resistance
4. low resistance to low resistance
Q41. The arrow in the symbol of a transistor indicates the direction of ………….
1. electron current in the emitter
2. electron current in the collector
3. hole current in the emitter
4. donor ion current
Q42. The leakage current in CE arrangement is ……………. that in CB arrangement
1. more than
2. less than
3. the same as
4. none of the above
Q43. A heat sink is generally used with a transistor to …………
1. increase the forward current
2. decrease the forward current
3. compensate for excessive doping
4. prevent excessive temperature rise
Q44. The most commonly used semiconductor in the manufacture of a transistor is
………….
1. germanium
2. silicon
3. carbon
4. none of the above
Q45. The collector-base junction in a transistor has ……………..
1. forward bias at all times
2. reverse bias at all times
3. low resistance
4. none of the above
Q46. When transistors are used in digital circuits they usually operate in the ………….
1. active region
2. breakdown region
3. saturation and cutoff regions
4. linear region
Q47. Three different Q points are shown on a dc load line. The upper Q point
represents the ………….
1. minimum current gain
2. intermediate current gain
3. maximum current gain
4. cutoff point
Q48. A transistor has a of 250 and a base current, IB, of 20 A. The collector
current, IC, equals to …………….
1. 500 μA
2. 5 mA
3. 50 mA
4. 5A
Q49. A current ratio of IC/IE is usually less than one and is called …………
1. beta
2. theta
3. alpha
4. omega
Q50. With the positive probe on an NPN base, an ohmmeter reading between the other
transistor terminals should be ……
1. open
2. infinite
3. low resistance
4. high resistance
Q51. In a CE configuration, an emitter resistor is used for ……
1. stabilization
2. ac signal bypass
3. collector bias
4. higher gain
Q52. Voltage-divider bias provides ……….
1. an unstable Q point
2. a stable Q point
3. a Q point that easily varies with changes in the transistor’s current gain
4. a Q point that is stable and easily varies with changes in the transistor’s current gain
Q53. To operate properly, a transistor’s base-emitter junction must be forward biased
with reverse bias applied to which junction?
1. collector-emitter
2. base-collector
3. base-emitter
4. collector-base
Q54. The ends of a load line drawn on a family of curves determine ……
1. saturation and cutoff
2. the operating point
3. the power curve
4. the amplification factor
Q55. If VCC = +18 V, voltage-divider resistor R1 is 4.7 k , and R2 is 1500 , then
the base bias voltage is ……….
1. 8.7 V
2. 4.35 V
3. 2.9 V
4. 0.7 V
Q56. The C-B configuration is used to provide which type of gain?
1. voltage
2. current
3. resistance
4. power
Q57. The Q point on a load line may be used to determine …………
1. VC
2. VCC
3. VB
4. IC
Q58. A transistor may be used as a switching device or as a ………….
1. fixed resistor
2. tuning device
3. rectifier
4. variable resistor
Q59. If an input signal ranges from 20–40 A (microamps), with an output signal
ranging from .5–1.5 mA (milliamps), what is the ac beta?
1. 0.05
2. 20
3. 50
4. 500
Q60. Beta’s current ratio is ……..
1. IC/IB
2. IC/IE
3. IB/IE
4. IE/IB
Answer: 1
Q61. A collector characteristic curve is a graph showing ………..
1. emitter current (IE) versus collector-emitter voltage (VCE) with (VBB) base bias voltage held
constant
2. collector current (IC) versus collector-emitter voltage (VCE) with (VBB) base bias voltage held
constant
3. collector current (IC) versus collector-emitter voltage (VC) with (VBB) base bias voltage held
constant
4. collector current (IC) versus collector-emitter voltage (VCC) with (VBB) base bias voltage held
constant
Q62. With low-power transistor packages, the base terminal is usually the ……….
1. tab end
2. middle
3. right end
4. stud mount
Q63. When a silicon diode is forward biased, VBE for a CE configuration is ……..
1. voltage-divider bias
2. 0.4 V
3. 0.7 V
4. emitter voltage
Q64. What is the current gain for a common-base configuration where IE = 4.2 mA and
IC = 4.0 mA?
1. 16.8
2. 1.05
3. 0.2
4. 0.95
Q65. With a PNP circuit, the most positive voltage is probably …………
1. ground
2. VC
3. VBE
4. VCC
Q66. If a 2 mV signal produces a 2 V output, what is the voltage gain?
1. 0.001
2. 0.004
3. 100
4. 1000
Q67. Most of the electrons in the base of an NPN transistor flow …………
1. out of the base lead
2. into the collector
3. into the emitter
4. into the base supply
Q68. In a transistor, collector current is controlled by ………..
1. collector voltage
2. base current
3. collector resistance
4. all of the above
Q69. Total emitter current is …………
1. IE – IC
2. IC + IE
3. IB + IC
4. IB – IC
Q70. Often a common-collector will be the last stage before the load; the main
function(s) of this stage is to ………….
1. provide voltage gain
2. provide phase inversion
3. provide a high-frequency path to improve the frequency response
4. buffer the voltage amplifiers from the low-resistance load and provide impedance matching
for maximum power transfer
Q71. For a CC configuration to operate properly, the collector-base junction should be
reverse biased, while forward bias should be applied to …………… junction.
1. collector-emitter
2. base-emitter
3. collector-base
4. cathode-anode
Q72. The input/output relationship of the common-collector and common-base
amplifiers is ………..
1. 270 degrees
2. 180 degrees
3. 90 degrees
4. 0 degrees
Q73. If a transistor operates at the middle of the dc load line, a decrease in the current
gain will move the Q point ………….
1. off the load line
2. nowhere
3. up
4. down
Q74. Which is the higher gain provided by a CE configuration?
1. voltage
2. current
3. resistance
4. power
Q75. What is the collector current for a CE configuration with a beta of 100 and a base
current of 30 A
1. 30
2. 0.3
3. 3 mA
4. 3 MA
