FSc ICS MCAT ECAT Physics Second Year Chapter 18 Electronics Multiple Choice Question (MCQ) Notes 2nd Year Physics Notes Online Taleem Ilmi Hub
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1. The gate, which performs the operation of inversion is called:
- NOT gate
- AND gate
- OR gate
- XOR gate
2. The gate, which changes the logic level to its opposite level is called:
- NOR gate
- AND gate
- OR gate
- NOT gate
3. If both the inputs given to a gate are 1, such that the output is 0 then it is:
- NAND gate
- NOR gate
- XOR gate
- All of these
4. If both the inputs given to a gate are 0 such that the output is 1 then it is:
- NAND gate
- NOR gate
- XNOR gate
- All of these
5. XNOR gate can be made by combining:
- OR, NOR, NOT gate
- OR, AND, NOT gate
- OR, NAND, NAND gate
- NOR, AND, NOT gate
6. Breakdown voltage is:
- 25 V
- 15 V
- 35 V
- 5 V
7. The value of reverse current for Ge is:
- 1 micro Ampere
- 1 milli Ampere
- 1 Ampere
- 1 Mega Ampere
8. Device used for conversion of D.C. to A.C. is:
- Oscillator
- Rectifier
- Amplifier
- None
9. p-n junction when reversed biased acts as a:
- Capacitor
- On switch
- Off switch
- None
10. Pulsating D.C. can be made smooth by using a circuit known as:
- Filter
- Tank
- Accepter
- All
11. A photodiode can switch its current on Or off in:
- nano second
- milli second
- micro second
- centi second
12. Photodiode is used in:
- Automatic switch
- Optical communication equipment
- Light meters
- All
13. Current gain of a transistor which has collector current of 10 mA and a base current of 40 micro Ampere is:
- 25
- 250
- 2500
- 25000
14. In case of common emitter amplifier, phase difference between input and output:
- 0 degree
- 120 degree
- 180 degree
- 90 degree
15. When transistor acts as OFF switch then voltage across collector and emitter is _____ Vcc.
- Less than
- Greater than
- Equal to
- None
16. The photovoltaic cell is always:
- Forward biased
- Reverse biased
- No biasing is required
- None
17. Under ideal conditions, the collector current is:
- Equal to base current
- Nearly equal to emitter current
- Less than base current
- Always zero
18. One use of a single p-n junction semiconductor in an electrical circuit is a:
- Rectifier
- Transistor
- Battery
- Diode
19. The output from a full wave rectifier is:
- An AC voltage
- A DC voltage
- Zero
- A pulsating unidirectional voltage
20. When n-type semiconductor is heated:
- Number of electrons increases while holes decreases
- Number of holes increases while electrons decreases
- Holes and electrons remains same
- Holes and electrons increases equally
21. Zener diode is used for:
- Rectification
- Amplification
- Stabilization
- Modulation
22. In a semi-conducting diode, the reverse biased current is due to drift of free electrons and holes caused by:
- Thermal excitations only
- Impurity atoms only
- Both first and second
- Neither first nor second
23. In the reverse biased p-n junction, the current is of the order of:
- Ampere
- Milliampere
- Microampere
- Nanoampere
24. To measure light intensity we use:
- LED with forward bias
- LED with reverse bias
- Photodiode with reverse bias
- Photodiode with forward bias
25. On increasing the reverse bias to a large value in a p-n junction diode current:
- Increases slowly
- Remains fixed
- Suddenly increases
- Decreases slowly
26. Rectifier is used to convert:
- Electrical energy to mechanical energy
- Heat energy into electrical energy
- High voltage into low voltage
- AC into DC
27. In an n-p-n transistor p-type crystal acts as:
- Emitter only
- Base only
- Collector only
- Either emitter or collector
28. The emitter base junction in the transistor is:
- Forward biased
- Reverse biased
- Either forward or reverse biased
- Neither forward nor reverse biased
29. The current gain of common-base transistor amplifier is:
- Less than one
- More than one
- Equal to one
- Zero
30. In common-base transistor amplifier. the phase difference between output voltage and input voltage is:
- Zero
- 180 degree
- 90 degree
- 45 degree
31. For a common base transistor amplifier the numerical value is least for:
- Voltage gain
- Power gain
- Resistance gain
- Current gain
32. The base of the transistor is made thin and is doped with least impurity atoms, because:
- About 95% charge carriers may cross
- !00% charge carriers may cross
- the transistor may be saved from high currents
- None of these
33. A logic gate is an electronic circuit which:
- Makes logic decisions
- Allow electron flow only in one direction
- Allows hole flow only in one direction
- Alternates between 0 an 1 value
34. Digital circuits can be made by respective use of:
- AND gates
- OR gates
- NOT gates
- NAND gates
35. Which logic function has the output low only when inputs are high?
- OR
- NOR
- AND
- NAND
36. In a half wave rectifier the rms value of AC component of the waves:
- Zero
- Equal to DC value
- More than DC value
- Less than DC value
37. A PN junction has a thickness of the order of:
- 10(-12) m
- 10(-6) m
- 1 mm
- 1 cm
38. A hole in a p-type semi-conductor is:
- A donor level
- An excess electron
- Missing electron
- A missing atom
39. If PN junction is forward biased its resistance is:
- Zero
- Infinity
- A few ohm
- A few kilo ohms
40. A part of transistor which is heavily doped to produce large number of majority carriers is:
- Emitter
- Base
- Collector
- May be any one
41. How is emitter base junction in the transistor biased?
- Forward
- Reverse
- May be forward or reverse
- None
42. The potential barrier of silicon diode is:
- 0.3 V
- 0.5 V
- 0.7 V
- 0.9 V
43. If collector current is 10 mA and base current of 10 microA. What is the current gain of transistor?
- 250
- 500
- 1000
- None of these
44. An op-amplifier can be used as:
- Inverting amplifier
- Night switch
- Comparator
- All
45. The output of two input OR gate is zero only when:
- Both are one
- Both are zero
- Either input is 1
- None
46. The semi-conductor used for fast counting in electronic circuit is:
- Photodiode
- LED
- Photovoltaic cell
- Solar cell
47. For normal transistor operation Ie is given by:
- Ie = Ic
- Ie = Ic + Ib
- Ie = Ib
- None
48. The value of open loop gain value for the amplifier is:
- Zero
- Infinity
- Very high
- Very low
49. The gate will recognized the voltage as 1 if the applied voltage to gate is:
- 1.5 V
- 0.5 V
- 3.5 V
- 0.7 V
50. In the depletion region of an unbiased PN junction diode there are:
- Only electrons
- Only holes
- Both holes and electrons
- Ions
51. In a transistor, the conventional current flows from base to emitter. The transistor is:
- NPN
- PNP
- FET
- None of these
52. In full wave rectifier with input frequency 50 Hz the ripple in the output is mainly of frequency:
- 25 Hz
- 50 Hz
- 100 Hz
- Zero
53. What is the voltage gain in a common emitter amplifier where input resistance is 3 ohm and load resistance 24 ohm, β = 0.6?
- 8.4
- 4.8
- 2.4
- 480
54. How many NAND gates are used to form AND gate?
- 1
- 2
- 3
- 4
55. Photodiode operates when it is:
- Forward biased
- Reverse biased
- Unbiased
- None
56. The open loop gain of op-amp is of the order of:
- 10(3)
- 10(4)
- 10(5)
- 10(6)
57. In a forward biased p-n junction diode, current inside the junction diode is due to drift of:
- Free electrons
- Both types of majority carriers
- Both types of minority carriers
- Donor atoms
58. A p-n junction diode cannot be used for:
- Rectification
- Amplification
- Obtaining light radiation
- Detecting light intensity
59. In a semiconductor diode, p-side is earthed and to n-side is applied a potential of -2 volt; the diode shall:
- Conduct
- Not conduct
- Conduct partially
- Break down
60. In the symbol for a transistor, the arrow head points in the direction of flow of:
- Holes
- Electrons
- Majority carriers
- Minority carriers
61. The current gain of common-emitter transistor amplifier is:
- Less than one
- More than one
- Equal to one
- Zero
62. In a common-emitter transistor amplifier, the phase difference between output voltage input voltage is:
- Zero
- 180 degree
- 90 degree
- 45 degree
63. The emitter of a transistor is doped the heaviest because it:
- Acts as a supplier of charge carriers
- Dissipates maximum power
- has a large resistance
- has a small resistance
64. At room temperature, potential difference develops across the depletion region in case of silicon:
- 0.3 V
- 0.7 V
- 0.8 V
- 0.9 V
65. Width of depletion region is:
- 10(-8) m
- 10(-7) m
- 10(-6) m
- 10(-4) m
66. In photovoltaic cell current is _______ proportional to intensity of light.
- Directly
- Inversely
- Both first and second
- None
67. Silicon transistors are preferred because:
- High operating temperature
- Low leakage current
- Suited to high frequency circuits
- All
68. If Rc = 10 kΩ , rie = 1kΩ , β = 50 then gain of common emitter amplifier:
- 500
- 50
- 5
- None
69. If R1 = 10 Ωk and R2 = 100kΩ then gain of inverting amplifier is:
- 10
- -10
- 100
- None
70. Electronic circuits which implement various logic operations are called:
- Logic gates
- Boolean algebra
- Amplifier gain
- None
The answer to ques 5 is option b) AND, NOT, OR
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