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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.
| 8351. |
The number of bits of information required to indicate the correct selection of 3 independent consecutive events out of 75 equally probable events is |
| A. | 6.23 |
| B. | 18.69 |
| C. | 10.46 |
| D. | 24.92 |
| Answer» C. 10.46 | |
| 8352. |
The efficiency of a direct radiating cone type loudspeaker is about |
| A. | 5% |
| B. | 20% |
| C. | 50% |
| D. | 80% |
| Answer» B. 20% | |
| 8353. |
Which of the following circuits cannot be demodulate SSB? |
| A. | Product detector |
| B. | Balanced modulator |
| C. | Phase discriminator |
| D. | BFO |
| Answer» D. BFO | |
| 8354. |
Figure shows the arrangement of |
| A. | FM |
| B. | PM |
| C. | AM-DSB |
| D. | AM-SSB |
| Answer» D. AM-SSB | |
| 8355. |
Consider the following statements as regards SAW filter The centre frequency is determined by the pitch of IDT comb shaped electrodesThe response can be modified shaping the overlap of comb electrodesThe response is maximum when acoustic wave has its wavelength equal to pitchWhen a number of identical electrodes are arranged at the same pitch, the frequency characteristics of the filter is expressed by (sin x)/x Which of the above statements are correct? |
| A. | 1, 2, 3, 4 |
| B. | 1, 2, 3 only |
| C. | 1, 2, 4 only |
| D. | 2, 3, 4 only |
| Answer» D. 2, 3, 4 only | |
| 8356. |
In telephone, the dial tone has a frequency of |
| A. | 5 Hz |
| B. | 15 Hz |
| C. | 33 Hz |
| D. | 233 Hz |
| Answer» D. 233 Hz | |
| 8357. |
Companding is used |
| A. | to overcome quantising noise in PCM |
| B. | in PWM receivers to reduce impulse noise |
| C. | to protect small signals in PCM from quantising noise |
| D. | none of the above |
| Answer» C. to protect small signals in PCM from quantising noise | |
| 8358. |
For a good public address system the sound intensity at the farthest point should be at least |
| A. | 20 dB over threshold of hearing |
| B. | 40 dB over threshold of hearing |
| C. | 80 dB over threshold of hearing |
| D. | 120 dB over threshold of hearing |
| Answer» D. 120 dB over threshold of hearing | |
| 8359. |
In FDM systems used for telephone, which modulation scheme is adopted? |
| A. | AM |
| B. | DSB-SC |
| C. | SSB-SC |
| D. | FM |
| Answer» E. | |
| 8360. |
In the above case if another sine wave corresponding to 40% modulation is transmitted simultaneously, the total radiated power will be |
| A. | 9.9 kW |
| B. | 10.15 kW |
| C. | 10.84 kW |
| D. | 18.4 kW |
| Answer» D. 18.4 kW | |
| 8361. |
A pre-emphasis circuit |
| A. | boosts base frequencies |
| B. | pre amplifies the complete audio band |
| C. | amplifies higher audio frequencies |
| D. | converts FM into phase modulation |
| Answer» D. converts FM into phase modulation | |
| 8362. |
An ungrounded antenna near the ground |
| A. | is horizontally polarized |
| B. | acts as an antenna array |
| C. | acts as a single antenna of twice the height |
| D. | is not likely to need an earth mat |
| Answer» D. is not likely to need an earth mat | |
| 8363. |
In orthogonal BFSK, the energy of information bearing term is |
| A. | the same as total transmitted energy |
| B. | one-half of total transmitted energy |
| C. | one-fourth of total transmitted energy |
| D. | none of the above |
| Answer» C. one-fourth of total transmitted energy | |
| 8364. |
MTI stands for |
| A. | Moving Target Indicator |
| B. | Microprocessor Tracking Index |
| C. | Multiplexed Telemetry Index |
| D. | Maximum Transmission Index |
| Answer» B. Microprocessor Tracking Index | |
| 8365. |
The IF frequencies in a TV receiver |
| A. | 38.9 MHz for video and 33.4 MHz for audio |
| B. | 38.9 MHz for both video and audio |
| C. | 33.4 MHz for both video and audio |
| D. | 33.4 MHz for video and 38.9 MHz for audio |
| Answer» B. 38.9 MHz for both video and audio | |
| 8366. |
In a tape recorder |
| A. | both record and erase heads have high permeability core |
| B. | the record head has high permeability core but the erase head has low permeability core |
| C. | the record head has low permeability core but the erase head has high permeability core |
| D. | both record and erase heads have low permeability core |
| Answer» B. the record head has high permeability core but the erase head has low permeability core | |
| 8367. |
The message carrying efficiency is best in |
| A. | AM |
| B. | FM |
| C. | AM-SC |
| D. | Phase modulation |
| Answer» D. Phase modulation | |
| 8368. |
The most noise resistant modulation system is |
| A. | PCM |
| B. | SSB suppressed carrier |
| C. | FM |
| D. | pulse position modulation |
| Answer» B. SSB suppressed carrier | |
| 8369. |
Which of the following is the digital system? |
| A. | PWM |
| B. | PAM |
| C. | PPM |
| D. | PCM |
| Answer» E. | |
| 8370. |
Which of the following is an oscillator with best frequency stability? |
| A. | Crystal oscillator |
| B. | Clapp oscillator |
| C. | Phase shift circuit |
| D. | Multivibrator |
| Answer» B. Clapp oscillator | |
| 8371. |
An SSB-AM signal cannot be demodulated by |
| A. | Balanced modulator |
| B. | Complete phase shift generator |
| C. | Diode balanced modulator |
| D. | Product detector |
| Answer» B. Complete phase shift generator | |
| 8372. |
The modulation index of wideband FM signal is |
| A. | less than unity |
| B. | unity |
| C. | greater than unity |
| D. | nearly 0.67 |
| Answer» D. nearly 0.67 | |
| 8373. |
The pre-emphasis circuit is used |
| A. | prior to modulation |
| B. | after demodulation |
| C. | for low frequency components of the signal |
| D. | none of the above |
| Answer» B. after demodulation | |
| 8374. |
Consider the following statements as regards DPSK and DEPSK DPSK demodulator requires a device which operates at carrier frequency and provides a delay of bit time TbIn DPSK, synchronous demodulation recovers the signal b(t) and the decoding of b(t) to generate d(t) is done at base bandIn both DPSK and DEPSK errors always occur in pairs Which of the above statements are correct? |
| A. | 1 and 3 |
| B. | 1 and 2 |
| C. | 2 and 3 |
| D. | 1, 2 and 3 |
| Answer» C. 2 and 3 | |
| 8375. |
An audio frequency of 5 kHz is translated to a radio frequency carrier of frequency 1 MHz and transmitted it to space through an antenna. The required height of antenna is |
| A. | 150 m |
| B. | 300 m |
| C. | 75 m |
| D. | 600 m |
| Answer» B. 300 m | |
| 8376. |
Pre-emphasis circuit is used |
| A. | after modulation |
| B. | before modulation |
| C. | before detection |
| D. | after detection |
| Answer» C. before detection | |
| 8377. |
In which frequency range is the noise figure in a transistor minimum |
| A. | intermediate frequencies |
| B. | low frequencies |
| C. | high frequencies |
| D. | very high frequencies |
| Answer» B. low frequencies | |
| 8378. |
In commercial FM Broadcasting, A radio station transmitting the signal at 98.3 MHz, it is |
| A. | carrier frequency |
| B. | modulation frequency |
| C. | message frequency |
| D. | channel frequency |
| Answer» B. modulation frequency | |
| 8379. |
An antenna having a length of and grounded at one end is called |
| A. | Marconi antenna |
| B. | Yagi antenna |
| C. | Turnstile antenna |
| D. | None of the above |
| Answer» B. Yagi antenna | |
| 8380. |
The noise figure of individual stages of a two stage amplifier is 2.03 and 1.54 respectively. If gain of first stage is 62, the overall noise figure is |
| A. | 2.03 |
| B. | 2.055 |
| C. | 3.05 |
| D. | 6.05 |
| Answer» C. 3.05 | |
| 8381. |
Foster Seeley discriminator uses a |
| A. | single tuned circuit |
| B. | double tuned circuit with primary and secondary tuned to the same frequency |
| C. | double tuned circuit with primary and secondary tuned to the different frequency |
| D. | none of the above |
| Answer» B. double tuned circuit with primary and secondary tuned to the same frequency | |
| 8382. |
Sound wave travels as |
| A. | longitudinal waves |
| B. | transverse waves |
| C. | both longitudinal and transverse waves |
| D. | either longitudinal or transverse wave |
| Answer» E. | |
| 8383. |
FM signal can be generated by |
| A. | diode reactance modulator |
| B. | saturable reactor modulator |
| C. | reactance tube modulator |
| D. | none of the above |
| Answer» E. | |
| 8384. |
A planar array radar uses a high gain planar array antenna. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8385. |
Which of the following statement about modulation is correct? |
| A. | It avoid use of antennas |
| B. | It reduces bandwidth |
| C. | It ensures transmission over long distances |
| D. | It combines different transmissions |
| Answer» D. It combines different transmissions | |
| 8386. |
In a system using QASK and 4 bits to form a symbol, the required bandwidth is |
| A. | same as BPSK |
| B. | half of that in BPSK |
| C. | one-fourth of that in BPSK |
| D. | none of the above |
| Answer» D. none of the above | |
| 8387. |
Assertion (A): Radio transmission is by sky wavesReason (R): Waves having frequencies higher than 30 MHz penetrate the atmosphere and do not return to earth. |
| A. | Both A and R are correct and R is correct explanation of A |
| B. | Both A and R are 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» C. A is correct but R is wrong | |
| 8388. |
During playback the take up reel is |
| A. | in clockwise motion |
| B. | in anticlockwise motion |
| C. | either clockwise or anticlockwise motion |
| D. | none of the above |
| Answer» C. either clockwise or anticlockwise motion | |
| 8389. |
Each of the following statements regarding frequency modulation is true except |
| A. | amplitude of the modulated wave remains the same as that of carrier wave |
| B. | the amount of variation of deviation from the original carrier frequency is determined by the frequency of the modulating signal |
| C. | the rate at which the frequency of modulated wave varies is determined by the frequency of the modulating signal |
| D. | frequency of modulated wave increases as the signal voltage increases and vice-versa |
| Answer» C. the rate at which the frequency of modulated wave varies is determined by the frequency of the modulating signal | |
| 8390. |
In a TV studio the illuminance is about |
| A. | 200 lux |
| B. | 1000 lux |
| C. | 10000 lux |
| D. | 10 lux |
| Answer» C. 10000 lux | |
| 8391. |
To avoid objectionable noise in a microwave TV link, the SNR should be about |
| A. | 50 or more |
| B. | 10 or more |
| C. | 25 or more |
| D. | 200 or more |
| Answer» D. 200 or more | |
| 8392. |
The decoder for PAL system is |
| A. | similar to NTSC decoder |
| B. | similar to NTSC decoder supplemented by 64 ms delay line |
| C. | similar to NTSC decoder supplemented by 64 ms delay line and an electronic commutator |
| D. | either (b) or (c) |
| Answer» D. either (b) or (c) | |
| 8393. |
Brownian motion is |
| A. | random emission of electrons in vacuum tubes |
| B. | thermal motion of electrons in a resistance |
| C. | random diffusion of holes and electrons in semi- conductors |
| D. | both (b) and (c) |
| Answer» C. random diffusion of holes and electrons in semi- conductors | |
| 8394. |
CW Doppler radar is capable of giving accurate measurements of relative velocities. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8395. |
In a radar, the return echo arrives after the allocated pulse interval. Then |
| A. | the receiver may be over loaded |
| B. | the target will appear closer than its actual position |
| C. | the return echo may interfere with transmitter operation |
| D. | none of the above |
| Answer» C. the return echo may interfere with transmitter operation | |
| 8396. |
MEWS stands for |
| A. | Missile Early Warning System |
| B. | Moving Target Early warning System |
| C. | Missile Early Warning Signal |
| D. | Moving Target Early Warning Signal |
| Answer» B. Moving Target Early warning System | |
| 8397. |
Top loading in an antenna increases |
| A. | effective height |
| B. | beam width |
| C. | input capacitance |
| D. | bandwidth |
| Answer» B. beam width | |
| 8398. |
As EM waves travel in free space they get |
| A. | reflected |
| B. | refracted |
| C. | attenuated |
| D. | absorbed |
| Answer» D. absorbed | |
| 8399. |
Cross talk is due to reception of portions of a signal from one channel into another. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8400. |
In the above case the total power in the modulated wave double sideband, suppressed carrier AM will be |
| A. | 112 W |
| B. | 400 W |
| C. | 415 W |
| D. | 512 W |
| Answer» C. 415 W | |