MCQOPTIONS
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MCQOPTIONS
This section includes 142 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering Physics knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
In a full-wave rectifier, the current in each diode flows for |
| A. | whole cycle of the input signal |
| B. | half cycle of the input signal |
| C. | more than half cycle of the input signal |
| D. | none of these |
| Answer» C. more than half cycle of the input signal | |
| 52. |
On the basis of energy band theory, semiconductors have an almost _____[1] valence band and an almost _____[2] conduction band and ____[3] forbidden energy gap |
| A. | [1]full, [2] empty,[3]narrow |
| B. | [1]empty, [2]full,[3]big |
| C. | [1]full,[2]full,[3]no |
| D. | [1]empty,[2]empty,[3]narrow |
| Answer» B. [1]empty, [2]full,[3]big | |
| 53. |
In silicon, ____________ energy must be supplied to push the electron from valance band to conduction band. |
| A. | 0.7 eV |
| B. | 1.1 eV |
| C. | 0.1 eV |
| D. | 0.3 eV |
| Answer» C. 0.1 eV | |
| 54. |
Consider the following statements:1. Fermi level in a p-type semiconductor lies close to the top of the valence bond.2. The forbidden energy in Germanium at 0 K is exactly 0.71 eV.3. When a p-n junction is reverse biased, then electrons and holes move away from the junction.Which of these statements are correct? |
| A. | 1, 2, and 3 |
| B. | 1 and 2 only |
| C. | 2 and 3 only |
| D. | 1 and 3 only |
| Answer» B. 1 and 2 only | |
| 55. |
Following are the semiconductor materials having certain values of recombination co-efficient.(a) GaP(b) Si(c) InAs(d) GaAsThe correct sequence in ascending order of their values are: |
| A. | (b), (a), (c), (d) |
| B. | (d), (b), (a), (c) |
| C. | (a), (b), (c), (d) |
| D. | (c), (b), (a), (d) |
| Answer» B. (d), (b), (a), (c) | |
| 56. |
A semiconductor differs from a conductor in that it has |
| A. | Only one path for the free electrons in the valence band |
| B. | Only one path for holes in the conduction band |
| C. | Two paths followed by free electrons and holes, one an ordinary path in the conduction band and the other one an extraordinary path in the valence band, respectively |
| D. | Two paths followed by free electrons and holes, one an extraordinary path in the conduction band and the other one an ordinary path in valence band, respectively |
| Answer» D. Two paths followed by free electrons and holes, one an extraordinary path in the conduction band and the other one an ordinary path in valence band, respectively | |
| 57. |
Plastics are: |
| A. | good conductors of electricity |
| B. | high-density materials |
| C. | bad conductors of electricity |
| D. | good conductors of heat |
| Answer» D. good conductors of heat | |
| 58. |
A common emitter amplifier circuit, built using an npn transistor, is shown in the figure. Its dc current gain is 250, RC = 1 kΩ and VCC = 10 V. What is the minimum base current for VCE to reach saturation? |
| A. | 40 μA |
| B. | 100 μA |
| C. | 7 μA |
| D. | 10 μA |
| Answer» B. 100 μA | |
| 59. |
Ampere-second is the unit of |
| A. | e.m.f |
| B. | Power |
| C. | Electric charge |
| D. | Energy |
| Answer» D. Energy | |
| 60. |
How many valence electrons are possessed by Germanium? |
| A. | 0 |
| B. | 1 |
| C. | 4 |
| D. | 8 |
| Answer» D. 8 | |
| 61. |
Insulators have: |
| A. | Conducting paths |
| B. | an empty conduction band |
| C. | a large energy gap |
| D. | a full valence band |
| Answer» D. a full valence band | |
| 62. |
Epitaxial growth is best suited for growing __________. |
| A. | Polycrystalline silicon |
| B. | very thin single crystal layer on a substrate |
| C. | single crystals several inches in size |
| D. | single crystal of several mm in size |
| Answer» C. single crystals several inches in size | |
| 63. |
Gunn diode can replace reflex klystron in (a) Signal Generators(b) Frequency modulated power oscillators(c) Parametric amplifiers pumps |
| A. | (a) and (b) |
| B. | (a) alone |
| C. | (a), (b) and (c) |
| D. | (b) alone |
| Answer» D. (b) alone | |
| 64. |
Conduction bands and valence bands overlap in: |
| A. | Conductor |
| B. | Semiconductor |
| C. | Insulator |
| D. | None of these |
| Answer» B. Semiconductor | |
| 65. |
Conduction takes place when electrons jump from: |
| A. | The forbidden band to the valence band |
| B. | The valence band to the conduction band |
| C. | The valence band to the forbidden band |
| D. | The conduction band to the valence band |
| Answer» C. The valence band to the forbidden band | |
| 66. |
A p-type semiconductor is _______. |
| A. | positively charged |
| B. | negatively charged |
| C. | electrically neutral |
| D. | not used in semiconductor devices |
| Answer» D. not used in semiconductor devices | |
| 67. |
A n-type semiconductor is obtained if we dope ________. |
| A. | Silicon with a trivalent element |
| B. | Silicon with a pentavalent element |
| C. | a pentavalent element with Silicon |
| D. | a trivalent element with Silico n |
| Answer» C. a pentavalent element with Silicon | |
| 68. |
n-type silicon is obtained by |
| A. | Doping with tetravalent element |
| B. | Doping with pentavalent element |
| C. | Doping with trivalent element |
| D. | Doping with a mixture of trivalent and tetravalent element |
| Answer» C. Doping with trivalent element | |
| 69. |
In an extrinsic semiconductor doped with trivalent impurity,________________. |
| A. | both electrons and holes become majority carriers |
| B. | both electrons and holes become minority carriers |
| C. | electrons become the minority carriers and holes the majority carriers |
| D. | electrons become the majority carriers and holes the minority carriers |
| Answer» D. electrons become the majority carriers and holes the minority carriers | |
| 70. |
Directions: The following items consist of two statements, one labeled as “Assertion(A)” and the other labeled as “Reason(R)”. You are to examine the two statements carefully and decide if the Assertion(A) and the Reason(R) are individually true and if so whether the reason is a correct explanation of the assertion. Select your answer to these items using the codes given below and mark your answer accordingly.Assertion (A): The tunnel diode shows the negative differential resistance between peak voltage and valley voltage.Reason (R): In a tunnel diode, for a voltage larger than valley voltage, the current increases exponentially. |
| A. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
| B. | Both (A) and (R) are true, but (R) is not the correct explanation of (A). |
| C. | (A) is true, but (R) is false. |
| D. | (A) is false, but (R) is true. |
| Answer» C. (A) is true, but (R) is false. | |
| 71. |
How many OPAMPs are used in an instrumentation amplifier? |
| A. | 3 |
| B. | 4 |
| C. | 5 |
| D. | 6 |
| Answer» B. 4 | |
| 72. |
Electronic distribution of an Si atom |
| A. | 2, 10, 2 |
| B. | 2, 8, 4 |
| C. | 2, 7, 5 |
| D. | 2, 4, 8 |
| Answer» C. 2, 7, 5 | |
| 73. |
Acceptor impurity atoms in a semiconductor result in new __________. |
| A. | wide energy band |
| B. | narrow energy band |
| C. | discrete energy level just below conduction level |
| D. | discrete energy level just above valence level |
| Answer» E. | |
| 74. |
In a pure semiconductor, electric current is due to __________. |
| A. | holes alone |
| B. | electrons alone |
| C. | both holes and electrons |
| D. | valence electrons alone |
| Answer» D. valence electrons alone | |
| 75. |
At 300 K temperature, the fermi level of an N-type semiconductor is 0.3 eV below the conductor band. The new position of the Fermi level at 360 K will be _____ below the conduction band. |
| A. | 0.66 eV |
| B. | 0.03 eV |
| C. | 30 eV |
| D. | 0.36 eV |
| Answer» E. | |
| 76. |
In the figure with Zener diode, the currents through the series resistance and load resistance are respectively |
| A. | 9 mA, 14 mA |
| B. | 10 mA, 5 mA |
| C. | 14 mA, 5 mA |
| D. | 1 mA, 6 mA |
| Answer» D. 1 mA, 6 mA | |
| 77. |
Fermi level for an n-type semiconductor lies |
| A. | Near valence band |
| B. | Near conduction band |
| C. | In valence band |
| D. | In conduction band |
| Answer» C. In valence band | |
| 78. |
Leakage current in the Silicon semiconductor is in the order of |
| A. | Amps |
| B. | milli Amps |
| C. | micro Amps |
| D. | Nano Amps |
| Answer» E. | |
| 79. |
In order to rectify an alternating current one uses a: |
| A. | Thermocouple |
| B. | Diode |
| C. | Triode |
| D. | Transister |
| Answer» C. Triode | |
| 80. |
Ceramics do not possess: |
| A. | High melting point |
| B. | Brittleness |
| C. | Hardness |
| D. | Electrical conduction |
| Answer» E. | |
| 81. |
A DIAC has __________ PN terminals. |
| A. | Three |
| B. | Two |
| C. | Four |
| D. | None of the above |
| Answer» C. Four | |
| 82. |
How many valence electrons exist in Silicon? |
| A. | 4 |
| B. | 2 |
| C. | 12 |
| D. | 16 |
| Answer» B. 2 | |
| 83. |
Assertion (A): A high electron mobility transistor is based upon modulation-doped (GaAs - AlGaAs) single heterojunction structure.Reason (R): HEMT shows a very high noise figure and very low gain at very high microwave frequencies up to 70 GHz. |
| A. | Both (A) and (R) are true and (R) is the correct explanation of (A) |
| B. | Both (A) and (R) are true, but (R) is not the correct explanation of (A) |
| C. | (A) is true, but (R) is false |
| D. | (A) is false, but (R) is true |
| Answer» D. (A) is false, but (R) is true | |
| 84. |
Light is capable of transferring electrons to the free-state inside a material thus increasing the electrical conductivity of the material. When the energy imparted to the electrons is quite large, the latter may be emitted from the material into the surrounding medium. This phenomenon is known as |
| A. | Photoemissive effect |
| B. | Photovoltaic effect |
| C. | Photoconductivity effect |
| D. | photo absorptive effect |
| Answer» B. Photovoltaic effect | |
| 85. |
In forward bias, the width of potential barrier in a P-N junction diode |
| A. | Increases |
| B. | Decreases |
| C. | Remains constant |
| D. | First increases then decreases |
| Answer» C. Remains constant | |
| 86. |
For mercury arc rectifiers, the anode is usually made up of |
| A. | Aluminium |
| B. | Graphite |
| C. | Tungsten |
| D. | Copper |
| Answer» C. Tungsten | |
| 87. |
In a transistor the _________ is of moderate size and heavily doped. |
| A. | emitter |
| B. | junction |
| C. | base |
| D. | collector |
| Answer» B. junction | |
| 88. |
If the number of valence electrons in an atom is 4, what is the substance called? |
| A. | a conductor |
| B. | a semiconductor |
| C. | Neutral |
| D. | a bad conductor |
| Answer» C. Neutral | |
| 89. |
In a semiconductor device, if the Fermi level (EF) is positioned at the conduction band (Ec). Determine the approximate probability of finding electrons in states at (Ec + kT)(where k is Boltzmann constant and T is device temperature in Kelvin) |
| A. | 0.18 |
| B. | 0.27 |
| C. | 0.38 |
| D. | 0.52 |
| Answer» C. 0.38 | |
| 90. |
An emitter follower circuit works in |
| A. | Common emitter configuration |
| B. | Common base configuration |
| C. | Common collector configuration |
| D. | Common gate configuration |
| Answer» D. Common gate configuration | |
| 91. |
A zero level detector is a |
| A. | Limiter |
| B. | Peak detector |
| C. | Comparator with a trip point referenced to the bias voltage |
| D. | Comparator with a trip point referenced to zero |
| Answer» E. | |
| 92. |
An acceptor replacement atom in silicon might have n electrons in its outer shell. The value of n is: |
| A. | 6 |
| B. | 5 |
| C. | 4 |
| D. | 3 |
| Answer» E. | |
| 93. |
LED (a semi-conductor device) is an abbreviation that stands for |
| A. | Licence for Energy Dectector. |
| B. | Light Energy Device. |
| C. | Light Emitting Diode. |
| D. | Lost Energy Detector. |
| Answer» D. Lost Energy Detector. | |
| 94. |
Consider the following statements with regard to semiconductors:1. In n-type material free electron concentration is nearly equal to the density of donor atoms.2. 1 part in 108 donor type impurity added to Ge improves its conductivity at 30°C by a factor of 12.3. Phosphorus is an example of n-type impurity.4. Conductivity of Si is more sensitive to temperature than Ge.Which of these statements are correct? |
| A. | 1, 2 and 3 only |
| B. | 1, 3 and 4 only |
| C. | 2 and 4 only |
| D. | 1, 2, 3 and 4 |
| Answer» E. | |
| 95. |
Hall effect may not be used for which of the following? |
| A. | Detecting aircraft communication signals |
| B. | Determining the carrier concentration |
| C. | Determining whether the semiconductor is p or n type |
| D. | Calculating the mobility |
| Answer» B. Determining the carrier concentration | |
| 96. |
As per de Broglie’s relationship, the wavelength λ related to its mass m and velocity v is |
| A. | \(\frac{h}{{mv}}\) |
| B. | \(\frac{{hv}}{m}\) |
| C. | \(\frac{{hm}}{v}\) |
| D. | \(\frac{{mv}}{h}\) |
| Answer» B. \(\frac{{hv}}{m}\) | |
| 97. |
In an intrinsic semiconductor, the Fermi level: |
| A. | Lies at the center of forbidden energy gap. |
| B. | Is near the conduction band. |
| C. | Is near the valence band. |
| D. | May be anywhere in the forbidden energy gap. |
| Answer» B. Is near the conduction band. | |
| 98. |
Direction: Question consists of two statements, one labeled as the 'Assertion (A)' and the other as 'Reason (R)'. Examine these two statements carefully and select the answer to this question using the codes given below:Assertion (A): In an intrinsic semiconductor, the electron mobility in the conduction band is different from hole mobility in the valence band.Reason (R): In an intrinsic semiconductor, electrons and holes are created solely by thermal excitation across the energy gap. |
| A. | Both A and R are individually true and R is the correct explanation of A |
| B. | Both A and R are individually true but R is not the correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» C. A is true but R is false | |
| 99. |
In ____________ there is a large gap between the conduction band and the valence band. |
| A. | insulators |
| B. | metallic conductors |
| C. | elemental semiconductors |
| D. | compound semiconductors |
| Answer» B. metallic conductors | |
| 100. |
An intrinsic semiconductor at 0 K behaves as: |
| A. | A semiconductor |
| B. | An insulator |
| C. | A conductor |
| D. | A superconductor |
| Answer» C. A conductor | |