McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Electrical Engineering .
| 51. |
For dominant mode propagation in TE mode, if the rectangular waveguide has a broader dimension of 31.14 mm , then the cutoff wave number: |
| A. | 100 |
| B. | 500 |
| C. | 50 |
| D. | 1000 |
| Answer» A. 100 | |
| 52. |
The klystron tube used in a klystron amplifier is a _________ type beam amplifier. |
| A. | linear beam |
| B. | crossed field |
| C. | parallel field |
| D. | none of the mentioned |
| Answer» A. linear beam | |
| 53. |
A PIN diode consists of ______number of semiconductor layers. |
| A. | three |
| B. | two |
| C. | four |
| D. | one |
| Answer» A. three | |
| 54. |
The resistance of the PIN diode with positive bias voltage: |
| A. | increases |
| B. | decreases |
| C. | remains constant |
| D. | insufficient data |
| Answer» B. decreases | |
| 55. |
Microstrip line can support a pure TEM wave. |
| A. | true |
| B. | false |
| C. | microstrip supports only tm mode |
| D. | microstrip supports only te mode |
| Answer» B. false | |
| 56. |
The effective dielectric constant ∈r for a microstrip line: |
| A. | varies with frequency |
| B. | independent of frequency |
| C. | it is a constant for a certain material |
| D. | depends on the material used to make microstrip |
| Answer» B. independent of frequency | |
| 57. |
The arcs of circles on smith chart represent |
| A. | normalised resistance or conductance |
| B. | different values of swr |
| C. | normalised reactance or susceptance |
| D. | none of the above |
| Answer» C. normalised reactance or susceptance | |
| 58. |
The characteristic impedance of a transmission line is |
| A. | directly proportional to its length |
| B. | inversely proportional to its length |
| C. | independent of its length |
| D. | none of the above |
| Answer» C. independent of its length | |
| 59. |
Standing wave ratio (SWR) equal to unity implies that |
| A. | the transmission line is open circuited |
| B. | the transmission line is short circuited |
| C. | the transmission line\s characteristic impedance equals load impedance |
| D. | none of the above |
| Answer» C. the transmission line\s characteristic impedance equals load impedance | |
| 60. |
), The normalised load impedance is |
| A. | (1 + j 2) |
| B. | (2500 + j 5000) |
| C. | (0.5 +j) |
| D. | none of the above |
| Answer» A. (1 + j 2) | |
| 61. |
V and a conduction current of 1.2A is |
| A. | 25.2 |
| B. | 22.8 |
| C. | 28.8 |
| D. | 20 |
| Answer» D. 20 | |
| 62. |
and 9 respectively is |
| A. | 25 |
| B. | 1.33 |
| C. | 7 |
| D. | 0.75 |
| Answer» B. 1.33 | |
| 63. |
Input impedance of a shorted lossless line of length π/4 is |
| A. | zero |
| B. | infinity |
| C. | zo |
| D. | none of the above |
| Answer» C. zo | |
| 64. |
V. The SWR is |
| A. | 0.67 |
| B. | 1.2 |
| C. | 1 |
| D. | 1.5 |
| Answer» D. 1.5 | |
| 65. |
The reflection coefficient on a transmission line is 1/3, what is the SWR |
| A. | 0 |
| B. | 3 |
| C. | 2 |
| D. | 4 |
| Answer» C. 2 | |
| 66. |
pF/m and an inductance of 75 nH/m |
| A. | 5 ohm |
| B. | 50 ohm |
| C. | 500 ohm |
| D. | 5000 ohm |
| Answer» B. 50 ohm | |
| 67. |
The wavelength of a line with a phase constant of 3.14 units is |
| A. | 2 |
| B. | 1 |
| C. | 0.5 |
| D. | 3.14 |
| Answer» A. 2 | |
| 68. |
The dominant mode for rectangular waveguide is |
| A. | te11 |
| B. | tm11 |
| C. | te10 |
| D. | tm10 |
| Answer» C. te10 | |
| 69. |
Following waveguide component not easily adjustable for tuning |
| A. | stub |
| B. | iris |
| C. | screw |
| D. | plunger |
| Answer» B. iris | |
| 70. |
What is the wavelength of a wave in a waveguide? |
| A. | greater than in free space |
| B. | depends only on the waveguide dimensions and the free-space wavelength |
| C. | inversely proportional to the phase velocity |
| D. | inversely proportional to the group velocity |
| Answer» A. greater than in free space | |
| 71. |
What is the cut-off frequency of a waveguide? |
| A. | the highest frequency the waveguide operates |
| B. | the lowest frequency the waveguide operates |
| C. | the same as the operating frequency |
| D. | the only frequency the waveguide operates |
| Answer» B. the lowest frequency the waveguide operates | |
| 72. |
For reduction in cross sectional dimension, waveguide to use is |
| A. | ridged |
| B. | circular |
| C. | rectangular |
| D. | flexible |
| Answer» A. ridged | |
| 73. |
Out of following list, is not directional coupler |
| A. | bathe hole |
| B. | two hole |
| C. | rate race |
| D. | magic hole |
| Answer» D. magic hole | |
| 74. |
The condition which will satisfy the dimensions of the waveguide is |
| A. | a = b |
| B. | a>b |
| C. | a<b |
| D. | ab=0 |
| Answer» B. a>b | |
| 75. |
Materials generally preferred for wave guides are |
| A. | brass and aluminium |
| B. | cast iron and steel |
| C. | non-metallic solids including plastics |
| D. | all of the above |
| Answer» A. brass and aluminium | |
| 76. |
cm and b = 1.5 cm with μ = 1 and ε = 2.25 is |
| A. | 377 ohm |
| B. | 327 ohm |
| C. | 227 ohm |
| D. | 127 ohm |
| Answer» C. 227 ohm | |
| 77. |
75GHz? |
| A. | 9.2 cm |
| B. | 3.2 cm |
| C. | 0.6 m |
| D. | 12 cm |
| Answer» A. 9.2 cm | |
| 78. |
5 cm and 1 cm respectively is |
| A. | 4.5 ghz |
| B. | 5 ghz |
| C. | 5.5 ghz |
| D. | 6 ghz |
| Answer» D. 6 ghz | |
| 79. |
5 GHz is |
| A. | 1 cm |
| B. | 2 cm |
| C. | 3 cm |
| D. | 4 cm |
| Answer» B. 2 cm | |
| 80. |
A major disadvantage of klystron amplifier is |
| A. | low power gain |
| B. | low bandwidth |
| C. | high source power |
| D. | design complexity |
| Answer» B. low bandwidth | |
| 81. |
A PIN diode consists of........number of semiconductor layers. |
| A. | three |
| B. | two |
| C. | four |
| D. | one |
| Answer» A. three | |
| 82. |
The resistance of the PIN diode with positive bias voltage |
| A. | increases |
| B. | decreases |
| C. | remains constant |
| D. | insufficient data |
| Answer» B. decreases | |
| 83. |
GaAs is used in the fabrication of GUNN diodes because |
| A. | gaas is cost effective |
| B. | it less temperature sensitive |
| C. | it has low conduction band electrons |
| D. | less forbidden energy gap |
| Answer» D. less forbidden energy gap | |
| 84. |
The number of modes of operation for n type GaAs Gunn diode is |
| A. | two |
| B. | three |
| C. | four |
| D. | five |
| Answer» C. four | |
| 85. |
The number of semiconductor layers in IMPATT diode is: |
| A. | two |
| B. | three |
| C. | four |
| D. | none of the mentioned |
| Answer» C. four | |
| 86. |
The cavity resonator |
| A. | is equivalent to an lc resonant circuit |
| B. | in a reflect klystron has its output taken from the reflector plate |
| C. | produces a frequency which is independent of the cavity size. |
| D. | has a low q factor for narrow operation. |
| Answer» A. is equivalent to an lc resonant circuit | |
| 87. |
A traveling-wave tube (TWT) amplifies by virtue of |
| A. | the absorption of energy by the signal from an electron stream |
| B. | the effect of an external magnetic field |
| C. | the energy contained the cavity resonators |
| D. | the energy liberated form the collector |
| Answer» A. the absorption of energy by the signal from an electron stream | |
| 88. |
Which of the following is used as a high power microwave oscillator? |
| A. | thyratron |
| B. | magnetron |
| C. | klystron |
| D. | reflex-klystron |
| Answer» B. magnetron | |
| 89. |
The characterstic impedance of a transmission line depends upon |
| A. | shape of the conductor |
| B. | surface treatment of the conductor |
| C. | conductivity of the material |
| D. | geometrical configuration of conductors |
| Answer» D. geometrical configuration of conductors | |
| 90. |
In order to reduce skin effect at ultra high frequencies, |
| A. | conductors are painted |
| B. | conductors are anodized |
| C. | copper rodes with silver plating are used |
| D. | copper lubes with silver plating are used |
| Answer» D. copper lubes with silver plating are used | |
| 91. |
Which of the following are constants of transmission lines |
| A. | resistance |
| B. | inductance |
| C. | capacitance |
| D. | all of the above |
| Answer» D. all of the above | |
| 92. |
Indicate the false statement. The SWR on a transmission line is infinity; the line is
|
| A. | a short circuit |
| B. | an open circuit |
| C. | a complex impedance |
| D. | pure reactance |
| Answer» C. a complex impedance | |
| 93. |
Major advantage of a quarter wave transformer is |
| A. | proper matching |
| B. | high gain |
| C. | broader band width |
| D. | none of the above |
| Answer» C. broader band width | |
| 94. |
The reactances associated with the transmission line due to discontinuities: |
| A. | can be ignored |
| B. | have to be matched |
| C. | discontinuities do no exist |
| D. | none of the above |
| Answer» C. discontinuities do no exist | |
| 95. |
The wave impedance of air for a wave propagating in it is |
| A. | 377 Ω |
| B. | 345 Ω |
| C. | insufficient data |
| D. | none of the above |
| Answer» A. 377 Ω | |
| 96. |
A loss less line of characteristic impedance Z0 is terminated in pure reactance of -
|
| A. | 10 |
| B. | 2 |
| C. | 1 |
| D. | infinity |
| Answer» D. infinity | |
| 97. |
A rectangular air – filled waveguide has a cross section of 4 × 10 The
|
| A. | 1.5 ghz |
| B. | 2.5 ghz |
| C. | 2.0 ghz |
| D. | 3.0 ghz |
| Answer» A. 1.5 ghz | |
| 98. |
Indicate which one of the following modes do not exist in a rectangularresonant
|
| A. | te110 |
| B. | tm110 |
| C. | te011 |
| D. | mt111 |
| Answer» A. te110 | |
| 99. |
The phase velocity of waves propagation in hollow metal waveguide is |
| A. | greater than velocity of light in free space |
| B. | less than velocity of light in free space |
| C. | equal to velocity of light in free space |
| D. | equal to group velocity |
| Answer» C. equal to velocity of light in free space | |
| 100. |
The dominant mode in a rectangular waveguide is TE10 because this mode has |
| A. | no attenuation |
| B. | no cut off |
| C. | no magnetic field component |
| D. | the highest cut off wavelength |
| Answer» D. the highest cut off wavelength | |
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