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Chapter 18
ELECTRONICS
Encircle the most appropriate answer among the following options
1. Temperature coefficient of resistivity of a semi conductor is choose which one is correct:
(a) Constant
(b) Positive
(c) Negative
(d) Variable
2. The pn junction on forward biasing acts as choose which one is correct:
(a) Capacitor
(b) Low resistor
(c) Inductor
(d) High resistor
3. Which one of the following is not semi conductor choose which one is correct:
(a) Silicon
(b) Copper
(c) Gallium arsenide
(d) Germinium
4. The average gap for Germanium at OK is choose which one is correct:
(a) 1.12 ev
(b) 0.02 ev
(c) 6.72 ev
(d) 7.2 ev
5. The process of doping causes the resistivity of semi conductor to choose which one is correct:
(a) Decrease
(b) Remains constant
(c) Increase
(d) None of these
6. Depletion region has choose which one is correct:
(a) Electrons only
(b) Holes only
(c) Both electrons and holes
(d) Neither holes nor electrons
7 An n-type substance is choose which one is correct:
(a) Electrically neutral
(b) Negatively charged
(c) Positively charged
(d) None of these
8. Holes are exist in choose which one is correct:
(a) Conductors
(b) Semi conductors
(c) Insulators
(d) All of the above
9. A pn junction cannot be used as choose which one is correct:
(a) A detector
(b) A rectifier
(c) An amplifier
(d) None of these
10. Hole is equivalent to choose which one is correct:
(a) A positive charge
(b) A negative charge
(c) A neutral
(d) None of these
11. There is no current due to holes in good electrical conductors because they have choose which one is correct:
(a) Large forbidden energy gap
(b) No valance electron
(c) Overlapping valance & conduction band
(d) None of these
12. Silicon is the most commonly used choose which one is correct:
(a) Insulator
(b) Semi-conductor
(c) Dielectric
(d) Conductor
13. The crystal of Germinium or silicon in its pure form at absolute zero acts as choose which one is correct:
(a) Insulator
(b) Conductor
(c) Semi-conductor
(d) None of these
14. The crystal of germinium or silicon in its pure form at room temperature acts as choose which one is correct:
(a) Insulator
(b) Conductor
(c) Semi-conductor
(d) None of these
15. All the valence electrons present in a crystal of silicon are bounded in their orbits by choose which one is correct:
(a) Covalent bond
(b) Ionic bond
(c) Molecular bond
(d) None of these
16. Majority charge carries in the P-type region of p-n-junction are choose which one is correct:
(a) Protons
(b) Electrons
(c) Positrons
(d) Holes
17. The impurity in the germinium is usually in the ratio of choose which one is correct:
(a) 1 choose which one is correct:106
(b) 1 choose which one is correct:104
(c) 1 choose which one is correct:108
(d) 1 choose which one is correct:10 10
18. A potential barrier of 0.7V exists across p-n junction made from choose which one is correct:
(a) Silicon
(b) Germinium
(c) Indium
(d) Gallium
19. A Potential difference is developed across the depletion region of p-n junction due to choose which one is correct:
(a) Negative ions
(b) Positive ions
(c) Both positive and negative ions
(d) None of these
20. The external potential difference applied to p-n junction for forward biasing supplied energy to choose which one is correct:
(a) Free electrons in n region
(b) Holes in p-region
(c) Both free electrons and holes
(d) None of these
21. In forward biased situation, as the biasing voltage is increased, the current choose which one is correct:
(a) Does not change
(b) Decreases
(c) Also increases
(d) None of these
22. While drawing a graph between current and biasing voltage in p-n junction, the current is taken choose which one is correct:
(a) Along x-axis
(b) Along —y-axis
(c) Along x-axis and in mA
(d) Along +y-axis
23. In reverse biased, the resistance offered by the p-n junction is of the order of choose which one is correct:
(a) A few M
(b) Several M
(c) A few ohms
(d) None of these
24. The semi conductor diode has the property of choose which one is correct:
(a) Two way conduction
(b) Zero conduction
(c) One way conduction
(d) Amplification
25. Electrons present in P-type material due to thermal pair generation are choose which one is correct:
(a) Majority carriers
(b) Minority carriers
(c) Dual carriers
(d) None of these
26. Semi conductors with donor atoms and free electrons belong to the type choose which one is correct:
(a) n
(b) p
(c) Both n and P
(d) Any of above
27. P-n junction when reversed biased acts as a choose which one is correct:
(a) Capacitor
(b) Inductor
(c) On switch
(d) Off switch
28. In an n-type semi conductor there are choose which one is correct:
(a) Holes as majority carrier
(b) Immobile positive ions
(c) Immobile negative ions
(d) None of these
29. The width of depletion region of a junction choose which one is correct:
(a) Increase with inverse biasing
(b) Decrease with light doping
(c) Increase with heavy doping
(d) None of these
30. Which one of the following has the greatest energy gap choose which one is correct:
(a) Conductor
(b) Semi conductor
(c) Insulator
(d) None of these
31. Which one of the following has smallest energy gap choose which one is correct:
(a) Conductors
(b) Semi conductors
(c) Insulators
(d) None of these
32. Minority carries in n-type substances are choose which one is correct:
(a) Protons
(b) Electrons
(c) Neutrons
(d) Holes
33. Minority carriers in a p-type substances are choose which one is correct:
(a) Protons
(b) electrons
(c) Neutrons
(d) Holes
34. A junction between p and n materials forms choose which one is correct:
(a) An amplifier
(b) An oscillator
(c) A detector
(d) A semi conductor diode
35. Semi conductor diode conducts only when it is choose which one is correct:
(a) Reverse biased
(b) Forward biased
(c) Not biased
(d) None of these
36. The forward current through a semi conductor diode circuit is due to choose which one is correct:
(a) Electrons
(b) Holes
(c) Majority carriers
(d) Minority carriers
37. The reverse current through a semi conductor diode is due to choose which one is correct:
(a) Electrons
(b) Holes
(c) Majority can-iers
(d) Minority carriers
38. In pn junction, p-type end is basically referred as choose which one is correct:
(a) Anode
(b) Cathode
(c) Neutral
(d) None of these
39. In half wave rectification, the output DC voltage is obtained across the load for choose which one is correct:
(a) The negative half cycle Of input AC
(b) The positive half cycle Of input AC
(c) Both the input of AC
(d) None of the above
40. In full wave rectification, the output DC voltage is obtained across the load for choose which one is correct:
(a) The positive half cycle of input AC
(b) The negative half cycle of input AC
(c) Complete cycle of input AC
(d) None of these
41. Forward resistance of p-n junction is choose which one is correct:
(a) Few ohms
(b) Mega ohms
(c) Infinity
(d) Kilo ohms
42. Reverse resistance of p-n junction is choose which one is correct:
(a) Low
(b) Zero
(c) Very high
(d) None of these
43. Conversion of alternating current into direct current is called choose which one is correct:
(a) Modulation
(b) Amplification
(c) Oscillation
(d) Rectification
44. A region having zero charge particle choose which one is correct:
(a) Depletion region
(b) Potential difference
(c) Curved region
(d) None of above
45. The potential difference across depletion region in case of Si is choose which one is correct:
(a) 0.6 volt
(b) 0.9 volt
(c) 0.7 volt
(d) 0.2 volt
46. The potential difference across depletion region in case of Ge is choose which one is correct:
(a) 0.3 volt
(b) 0.7 volt
(c) 0.6 volt
(d) 0.8 volt
47. The most commonly used diode for special purpose is choose which one is correct:
(a) Light emitting diode
(b) Photo diode
(c) Photo voltaic cell
(d) All of above
48. A light emitting diode is made from choose which one is correct:
(a) Germinium
(b) Silicon
(c) Gallium arsenide
(d) Phosphorus
49. The number of LEDs required to display all the digits is choose which one is correct:
(a) Seven
(b) Five
(c) Six
(d) Eight
50. A photo diode can be used choose which one is correct:
(a) For detection of visible light
(b) For detection of invisible light
(c) Both (a) and (b)
(d) As an inductor
51. The diode used for the detection of visible and in visible light is choose which one is correct:
(a) Photodiode
(b) Photo voltaic cell
(c) Light emitting
(d) All of above
52. A diode, which can turn current ON and OFF in nanosecond is called choose which one is correct:
(a) Photo voltaic cell
(b) Light emitting diode
(c) Photodiode
(d) None of these
53. Photodiode is operated choose which one is correct:
(a) In the reversed biased situation
(b) In the forward biased situation
(c) With the light incident upon it
(d) Both (a) and (c)
54. Photo voltaic cell is also called choose which one is correct:
(a) Solar cell
(b) Generator
(c) Thermo couple
(d) Thermister
55. A single photovoltaic cell produces a current of choose which one is correct:
(a) 0.9v
(b) 0.6v
(c) 0.5v
(d) 6.0v
56. A single photo voltaic cell produces a current of choose which one is correct:
(a) A few mA
(b) A few A
(c) A few ampere
(d) 1A
57. The light emitting diode emits light when it is choose which one is correct:
(a) Reverse biased
(b) Forward biased
(c) Both (a) and (b)
(d) None of these
58. The specially designed semi conductor diodes used as indicator lamps in electronic circuits are choose which one is correct:
(a) The switch
(b) The light emitting diode
(c) The photo diode
(d) Solar cells
59. The specially designed semi-conductor used for as fast countings in electronic circuits will be choose which one is correct:
(a) Photo diodes
(b) Light emitting diode
(c) Photo voltaic cell
(d) Solar cell
60. A combination of p-type and N-type substance give rise to choose which one is correct:
(a) P-N junction
(b) N-N-junction
(c) P-P junction
(d) None of the above
61. When p-type of p-n-junction connected to positive end and N-type of the junction connected to the negative terminal of battery then the junction is choose which one is correct:
(a) Reverse biased
(b) Forward biased
(c) Neutral
(d) None of these
62. If a reverse current of a reverse biased junction is increased to a maximum value then choose which one is correct:
(a) Diode junction may break down
(b) Voltage drops to zero
(c) Voltage becomes maximum
(d) None of these
63. Operational-amplifier has been discussed as comparator of choose which one is correct:
(a) Voltage
(b) Current
(c) Displacement
(d) Electric fields
64. The semi conductor diode has the property of a choose which one is correct:
(a) Two way conduction
(b) One way conduction
(c) Zero conduction
(d) None of these
65. If positive terminal of the battery is connected to n-type and negative terminal is connected to p type then diode is choose which one is correct:
(a) Forward biased
(b) Reverse biased
(c) Zero biased
(d) Not biased
66. The process due to which current flows only during alternate half cycle is known as choose which one is correct:
(a) Half wave rectification
(b) Full wave rectification
(c) Saturation
(d) Amplification
67. The circuit of full wave rectification consist of choose which one is correct:
(a) Three diodes
(b) Four diodes
(c) Two diodes
(d) One diode
68. When transistor works as an amplifier, its output is choose which one is correct:
(a) Zero
(b) Greater
(c) Less
(d) Greater or less directly proportional to the input
69. An operational amplifier can be used as choose which one is correct:
(a) Night switch
(b) Comparator
(c) Inverting and non-inverting amplifier
(d) All of the above
70. An operational amplifier have how many input terminals choose which one is correct:
(a) Two
(b) Four
(c) Three
(d) Five
71. Transistor was discovered by choose which one is correct:
(a) John Bardeen
(b) I-carrie
(c) G Bell
(d) Young
72. A transistor has choose which one is correct:
(a) Two region
(b) One region
(c) Three region
(d) Four region
73. The operational amplifier is choose which one is correct:
(a) A high gain amplifier
(b) A high-power amplifier
(c) A high resistance amplifier
(d) A low resistance amplifier
74. The basic condition for a transistor amplifier circuit is choose which one is correct:
(a) The base-emitter junction should be forward biased
(b) The base-emitter junction should be reverse biased
(c) The base-collector junction should be forward biased
(d) None of these
75. Usually VBB is choose which one is correct:
(a) Larger than Vcc
(b) Smaller than Vcc
(c) Equal to Vcc
(d) None of these
76. In order that a transistor acts as switch, a larger positive potential is applied across its choose which one is correct:
(a) Base-collector terminals
(b) Base emitter terminals
(c) Collector emitter terminals
(d) None of these
77. To turn the transistor OFF, the base current is set choose which one is correct:
(a) At zero value
(b) At maximum value
(c) At minimum value
(d) None of these
78. Types of transistors are choose which one is correct:
(a) Seven
(b) Two
(c) Four
(d) Three
79. In the transistor schematic symbol, the arrow is choose which one is correct:
(a) Located on the base
(b) Located on the collector
(c) Located on the emitter
(d) None of these
80. The term transistor stands for choose which one is correct:
(a) Transfer of resistance
(b) Transfer of current
(c) Transfer of charge
(d) Transfer of energy
81. The transistor in a circuit basically acts as choose which one is correct:
(a) Power amplifier
(b) Current amplifier
(c) Voltage amplifier
(d) None of these
82. Transistor can be used as choose which one is correct:
(a) Oscillator
(b) Switches
(c) Units
(d) All of above
83. When a transistor is used in a circuit generally choose which one is correct:
(a) The collector-base junction is forward biased and the collector-base junction is reverse biased
(b) Both the junctions are forward biased
(c) Both the junction are reverse biased
(d) None of these
84. An operational amplifier will act as inverting amplifier, when the input signal is connected to choose which one is correct:
(a) Earthed wire
(b) Inverting terminal
(c) Non inverting terminal
(d) None of these
85. The characteristic of transistor are choose which one is correct:
(a) Temperature dependent
(b) Sound dependent
(c) Energy dependent
(d) Light dependent
86. Emitter base junction is always choose which one is correct:
(a) Forward biased
(b) Reverse biased
(c) Both forward and reverse
(d) None of these
87. The emitter and base has concentration of impurity choose which one is correct:
(a) Less
(b) Zero
(c) Greater
(d) None of these
88. Identify which device used the rectification choose which one is correct:
(a) Inductor
(b) Capacitor
(c) Transistor
(d) P-n junction
89. Which one of the following device based on p-n junction choose which one is correct:
(a) Photo diode
(b) Light emitting diode
(c) Photo voltaic cell
(d) All of the above
90. Light emitting diode based on choose which one is correct:
(a) Emission of energy in the form of photons
(b) Faradays law
(c) Ionic bonding between p-type and n-type substances
(d) None of these
91. Photo diode can be used as choose which one is correct:
(a) A automatic ON and OFF switch
(b) Direction of light
(c) Logic gates
(d) All of above
92. The central region of n-p-n transistor is known as choose which one is correct:
(a) Base
(b) Collector
(c) Emitter
(d) None of above
93. In general, most of the electrical circuits make use of choose which one is correct:
(a) n-n junction
(b) p-p junction
(c) n-p-n transistor
(d) p-n-p transistor
94. A transistor consists of three electrical contact which one of these is rectifying choose which one is correct:
(a) Chemically
(b) Electronically
(c) Electrically
(d) Mechanically
95. When light emitting diode is forward biased, it emits light of colour choose which one is correct:
(a) Yellow
(b) Green
(c) Red
(d) All of the above
96. The advantage of LEDs is choose which one is correct:
(a) High operating speed
(b) Small size
(c) Reliability
(d) All
97. In n-p-n transistor, the current flows in the direction from choose which one is correct:
(a) Base to emitter
(b) Collector to emitter
(c) Emitter to base
(d) Base to collector
98. In p-n-p transistor, the current flows in the direction from choose which one is correct:
(a) Base to emitter
(b) Emitter to collector
(c) Emitter to base
(d) Base to collector
99. In a transistor which one is very thin choose which one is correct:
(a) Base
(b) Collector
(c) Emitter
(d) None of these
100. The thickness of the base is of the order of choose which one is correct:
(a) 10-6 m
(b) 10-4 m
(c) 10-2 m
(d) 104 m