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MCQOPTIONS
This section includes 9294 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
A geosynchronous satellite |
| A. | has the same period a that of the Earth |
| B. | has a circular orbit |
| C. | rotates in the equatorial plane |
| D. | has all of the above |
| Answer» E. | |
| 52. |
Neutralization is used in RF amplifiers to |
| A. | stop oscillation |
| B. | increase bandwidth |
| C. | improve selectivity |
| D. | all of the above |
| Answer» B. increase bandwidth | |
| 53. |
The angle subtended by earth at geostationary communication satellite is |
| A. | 17.34 |
| B. | 51.4 |
| C. | 120 |
| D. | 60 |
| Answer» B. 51.4 | |
| 54. |
Which are the popular IF frequencies for microwave and radar receivers operating on frequencies in the range 1 to 10 GHz |
| A. | 30, 60 and 70 kHz |
| B. | 3, 6 and 7 kHz |
| C. | 30, 60 and 70 MHz |
| D. | 3, 6 and 7 GHz |
| Answer» D. 3, 6 and 7 GHz | |
| 55. |
A duplexer is a device used to |
| A. | feed more than one receiver from a single antenna |
| B. | connect two transmitters to the same antenna |
| C. | connect a receiver and a transmitter to the same antenna |
| D. | none of these |
| Answer» D. none of these | |
| 56. |
The discussing sharing of a communication satellite by many geographically dispersed Earth station, DAMA means |
| A. | Demand-Assigned Multiple Access |
| B. | Decibel Attenuated Microwave Access |
| C. | Digital Analog Master Antenna |
| D. | Dynamically-Assigned Multiple Access |
| Answer» B. Decibel Attenuated Microwave Access | |
| 57. |
It is known that noise phase modulates the FM wave. As the noise side band frequency approaches the carrier frequency, the noise amplitude |
| A. | will increase |
| B. | will decrease |
| C. | will remain constant |
| D. | will reduce to negligible value |
| Answer» C. will remain constant | |
| 58. |
In a broadcast superheterodyne receiver |
| A. | the local oscillator operates below the signal frequency |
| B. | local oscillator frequency is normally double the IF |
| C. | RF amplifier normally works at kHz above the carrier frequency |
| D. | mixer input must be tuned to the signal frequency |
| Answer» E. | |
| 59. |
A JK flip flop has tpd= 12 ns. The largest modulus of a ripple counter using these flip flops and operating at 10 MHz is |
| A. | 16 |
| B. | 64 |
| C. | 128 |
| D. | 256 |
| Answer» E. | |
| 60. |
The basic storage element in a digital system is |
| A. | flip flop |
| B. | counter |
| C. | multiplexer |
| D. | encoder |
| Answer» B. counter | |
| 61. |
The access time of a word in 4 MB main memory is 100 ms. The access time of a word in a 32 kb data cache memory is 10 ns. The average data cache bit ratio is 0.95. The efficiency of memory access time is |
| A. | 9.5 ns |
| B. | 14.5 ns |
| C. | 20 ns |
| D. | 95 ns |
| Answer» C. 20 ns | |
| 62. |
The expression Y = pM (0, 1, 3, 4) is |
| A. | POS |
| B. | SOP |
| C. | Hybrid |
| D. | none of the above |
| Answer» B. SOP | |
| 63. |
An 8 bit DAC has a full scale output of 2 mA and full scale error of 0.5%. If input is 10000000 the range of outputs is |
| A. | 994 to 1014 A |
| B. | 990 to 1020 A |
| C. | 800 to 1200 A |
| D. | none of the above |
| Answer» B. 990 to 1020 A | |
| 64. |
Decimal 43 in hexadecimal and BCD number system is respectively. |
| A. | B2, 01000011 |
| B. | 2B, 01000011 |
| C. | 2B, 00110100 |
| D. | B2, 01000100 |
| Answer» C. 2B, 00110100 | |
| 65. |
In a ripple counter, |
| A. | whenever a flip flop sets to 1, the next higher FF toggles |
| B. | whenever a flip flop sets to 0, the next higher FF remains unchanged |
| C. | whenever a flip flop sets to 1, the next higher FF faces race condition |
| D. | whenever a flip flop sets to 0, the next higher FF faces race condition |
| Answer» B. whenever a flip flop sets to 0, the next higher FF remains unchanged | |
| 66. |
In a step down chopper using pulse width modulation, Ton = 3 x 10-3 and Toff = 1 x 10-3 s. The chopping frequency is |
| A. | 333.33 |
| B. | 250 |
| C. | 500 |
| D. | 1000 |
| Answer» C. 500 | |
| 67. |
Thyristors are suitable for dc circuit breakers but not for ac circuit breakers. |
| A. | True |
| B. | False |
| Answer» C. | |
| 68. |
Assertion (A): Inverters and choppers use fast switching thyristors Reason (R): Fast switching SCR has low turn off time. |
| A. | Both A and R are correct and R is correct explanation of A |
| B. | Both A and R correct but R is not correct explanation of A |
| C. | A is correct but R is wrong |
| D. | A is wrong but R is correct |
| Answer» B. Both A and R correct but R is not correct explanation of A | |
| 69. |
The value of capacitor C for dynamic equalising circuit of series connected thyristors is determined by |
| A. | forward characteristics of thyristors |
| B. | reverse recovery characteristics of thyristors |
| C. | both forward and reverse recovery characteristics of thyristors |
| D. | none of the above |
| Answer» C. both forward and reverse recovery characteristics of thyristors | |
| 70. |
A chopper |
| A. | converts constant voltage dc into ac and then into variable voltage dc |
| B. | converts constant voltage dc into variable voltage dc directly |
| C. | converts ac of one frequency into ac of another frequency |
| D. | converts ac to dc |
| Answer» C. converts ac of one frequency into ac of another frequency | |
| 71. |
Assertion (A): If the duty cycle of chopper is low the current would not become discontinuousReason (R): If the time constant L/R of the load in chopper is low the current may become discontinuous. |
| A. | Both A and R are correct and R is correct explanation of A |
| B. | Both A and R correct but R is not correct explanation of A |
| C. | A is correct but R is wrong |
| D. | A is wrong but R is correct |
| Answer» D. A is wrong but R is correct | |
| 72. |
In a single phase full wave regulator, the firing angles in the positive and negative half cycles are generally |
| A. | equal |
| B. | different |
| C. | equal or different |
| D. | different but sometimes equal |
| Answer» B. different | |
| 73. |
An electric heater is controlled by thyristors through on-off control. If a = 0.4, the heating is |
| A. | 16% maximum |
| B. | 40% of maximum |
| C. | 60% of maximum |
| D. | 84% of maximum |
| Answer» C. 60% of maximum | |
| 74. |
A semiconverter feeding an RLE load operates in |
| A. | first quadrant only |
| B. | first and second quadrants |
| C. | first and fourth quadrants |
| D. | first and third quadrants |
| Answer» B. first and second quadrants | |
| 75. |
The phenomenon of overlap in converter operation due to |
| A. | source resistance |
| B. | source inductance |
| C. | both source resistance and source inductance |
| D. | high value of firing angle |
| Answer» C. both source resistance and source inductance | |
| 76. |
A thyristor has a maximum allowable junction temperature of 120 C and the ambient temperature is 40 C. If thermal resistance is 1.6 C/W, the maximum allowable internal power dissipation is |
| A. | 20 W |
| B. | 50 W |
| C. | 92 W |
| D. | 128 W |
| Answer» C. 92 W | |
| 77. |
The terminals of a power BJT are called |
| A. | emitter, base, collector |
| B. | emitter, base, drain |
| C. | source, base, drain |
| D. | source, base, collector |
| Answer» B. emitter, base, drain | |
| 78. |
In single phase half wave regulator, the average current over one full cycle |
| A. | is always positive |
| B. | may be positive or negative |
| C. | may be negative |
| D. | is always negative |
| Answer» E. | |
| 79. |
An SCR is triggered at 40 in the positive half cycle only. The average anode current is 50 A. If the firing angle is changed to 80 , the average anode current is likely to be |
| A. | 50 A |
| B. | 25 A |
| C. | less than 50 A but more than 25 A |
| D. | less than 25 A |
| Answer» D. less than 25 A | |
| 80. |
A rectangular metal waveguide filled with a dielectric of relative permittivity r = 4, has the inside dimensions 3 x 1.2 cm, the cut off frequency for the dominant mode is |
| A. | 2.5 GHz |
| B. | 5 GHz |
| C. | 10 GHz |
| D. | 12.5 GHz |
| Answer» C. 10 GHz | |
| 81. |
Noise temperature of Sun is more than __________ K. |
| A. | 1000 |
| B. | 5000 |
| C. | 100000 |
| D. | 500 |
| Answer» D. 500 | |
| 82. |
The function of an AM detector circuit is to |
| A. | rectify the input signal |
| B. | discard the carrier |
| C. | provide audio signal |
| D. | all of the above |
| Answer» E. | |
| 83. |
In a superheterodyne receiver |
| A. | the IF stage has better selectivity than RF stage |
| B. | the RF stage has better selectivity than IF stage |
| C. | the RF stage has same selectivity than IF stage |
| D. | none of the above |
| Answer» B. the RF stage has better selectivity than IF stage | |
| 84. |
Most popular IF for receivers tuning to 540 to 1650 kHz is |
| A. | 433 kHz |
| B. | 455 kHz |
| C. | 545 kHz |
| D. | 555 kHz |
| Answer» C. 545 kHz | |
| 85. |
The resolution of an n bit DAC with a maximum input of 5 V is 5 mV. The value of n is |
| A. | 8 |
| B. | 9 |
| C. | 10 |
| D. | 11 |
| Answer» D. 11 | |
| 86. |
2's complement of binary number 0101 is |
| A. | 1011 |
| B. | 1111 |
| C. | 1101 |
| D. | 1110 |
| Answer» B. 1111 | |
| 87. |
An OR gate has 4 inputs. One input is high and the other three are low. The output |
| A. | is low |
| B. | is high |
| C. | is alternately high and low |
| D. | may be high or low depending on relative magnitude of inputs |
| Answer» C. is alternately high and low | |
| 88. |
Decimal number 10 is equal to binary number |
| A. | 1110 |
| B. | 1010 |
| C. | 1001 |
| D. | 1000 |
| Answer» C. 1001 | |
| 89. |
Both OR and AND gates can have only two inputs. |
| A. | True |
| B. | False |
| Answer» C. | |
| 90. |
In the below figure the average load current is 15 A. The rms value of transformer secondary current is |
| A. | 15 A |
| B. | 10.61 A |
| C. | 7.5 A |
| D. | 14.14 A |
| Answer» C. 7.5 A | |
| 91. |
In a 3 phase fully controlled converter the firing frequency is |
| A. | 3 times the line frequency |
| B. | 6 times the line frequency |
| C. | 9 times the line frequency |
| D. | 12 times the line frequency |
| Answer» C. 9 times the line frequency | |
| 92. |
Two thyristor of same rating and same specifications |
| A. | will have equal turn on and turn off periods |
| B. | will have equal turn on but unequal turn off periods |
| C. | may have equal or unequal turn on and turn off periods |
| D. | will have unequal turn on and turn off periods |
| Answer» D. will have unequal turn on and turn off periods | |
| 93. |
The amount of dielectric heating is inversely proportional to frequency. |
| A. | True |
| B. | False |
| Answer» C. | |
| 94. |
ZL = 200 Ω and it is desired that Zi = 50 Ω The quarter wave transformer should have a characteristic impedance of |
| A. | 100 Ω |
| B. | 40 Ω |
| C. | 10000 Ω |
| D. | 4 Ω |
| Answer» B. 40 Ω | |
| 95. |
A broadside array consisting of 200 cm wavelength with 10 half-wave dipole spacing 10 cm. And if each array element feeding with 1 amp. current and operating at same frequency then find the half power beamwidth |
| A. | 4 |
| B. | 2 |
| C. | 10 |
| D. | 15 |
| Answer» C. 10 | |
| 96. |
Refractive index of glass is 1.5. Find the wavelength of a beam of light with a frequency of 1014 Hz in glass. Assume velocity of light is 3 x 108 m/sec in vacuum. |
| A. | 4 m |
| B. | 3 m |
| C. | 2 m |
| D. | 1 m |
| Answer» D. 1 m | |
| 97. |
The function f(x - vot) represent which of the following? |
| A. | A stationary wave |
| B. | A wave motion in forward direction |
| C. | A wave motion in reverse direction |
| D. | None of the above |
| Answer» C. A wave motion in reverse direction | |
| 98. |
A broadside array operating at 100 cm wavelength consist of 4 half-wave dipoles spaced 50 cm apart. Each element carries radio frequency current in the same phase and of magnitude 0.5 A. The radiated power will be |
| A. | 196 W |
| B. | 73 W |
| C. | 36.5 W |
| D. | 18.25 W |
| Answer» B. 73 W | |
| 99. |
If and A + B is |
| A. | <img src="/_files/images/electronics-and-communication-engineering/signals-and-systems/13-165-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/signals-and-systems/13-165-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/signals-and-systems/13-165-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/signals-and-systems/13-165-4.png"> |
| Answer» B. <img src="/_files/images/electronics-and-communication-engineering/signals-and-systems/13-165-2.png"> | |
| 100. |
A voltage V(t) is a Gaussian ergodic random process with a mean of zero and a variance of 4 volt2. If it is measured by a dc meter. The reading will be |
| A. | 0 |
| B. | 4 |
| C. | 2 |
| D. | <span class="root">2</span> |
| Answer» B. 4 | |