MCQOPTIONS
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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.
| 8251. |
If the AF voltage is raised to 10 V, while the AM is dropped to 200 Hz, what is the deviation? |
| A. | 10 kHz |
| B. | 15 kHz |
| C. | 20 kHz |
| D. | 40 kHz |
| Answer» D. 40 kHz | |
| 8252. |
Assertion (A): RF tuner is called front end of TV receiverReason (R): RF tuner receives the TV signal and selects the required channel. |
| 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» B. Both A and R are correct but R is not correct explanation of A | |
| 8253. |
The oscillator frequency is set for |
| A. | best picture |
| B. | max. sound |
| C. | min. sound |
| D. | sound in picture |
| Answer» B. max. sound | |
| 8254. |
The main advantage of DM over PCM is |
| A. | less bandwidth |
| B. | less power |
| C. | simple circuit |
| D. | better S/N ratio |
| Answer» D. better S/N ratio | |
| 8255. |
An FM signal is modulated by an 8 kHz sine wave and has maximum and minimum frequencies of 100.05 MHz and 99.95 MHz respectively. Its deviation frequency is |
| A. | 100 kHz |
| B. | 100 MHz |
| C. | 500 kHz |
| D. | 108 kHz |
| Answer» E. | |
| 8256. |
In TV broadcast, UHF range is |
| A. | 606 - 790 MHz |
| B. | 100 - 150 MHz |
| C. | 41 - 68 MHz |
| D. | 174 - 230 MHz |
| Answer» B. 100 - 150 MHz | |
| 8257. |
The most commonly used microphone for public address systems is |
| A. | carbon |
| B. | crystal |
| C. | moving coil |
| D. | condenser |
| Answer» D. condenser | |
| 8258. |
Pre-emphasis and De-emphasis is done by using R-C circuit. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8259. |
The minimum viewing angle of resolution of human eye is (D is iris opening and is wavelength of light) |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/506-244-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/506-244-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/506-244-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/506-244-4.png"> |
| Answer» C. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/506-244-3.png"> | |
| 8260. |
In FM, |
| A. | there is a large decrease in noise and hence increase in the signal to noise ratio |
| B. | there is a large increase in noise and hence decrease in the signal to noise ratio |
| C. | there is a large increase in noise and hence increase in the signal to noise ratio |
| D. | there is a large decrease in noise and hence decrease in the signal to noise ratio |
| Answer» B. there is a large increase in noise and hence decrease in the signal to noise ratio | |
| 8261. |
The power density spectrum of noise voltage of resistor R can be expressed as |
| A. | 2 kTR |
| B. | 1 kTR |
| C. | 0.5 kTR |
| D. | 0.25 kTR |
| Answer» B. 1 kTR | |
| 8262. |
The output of a battery eliminator is about |
| A. | 110 V DC |
| B. | 110 V AC |
| C. | 45 V DC |
| D. | 6 V DC |
| Answer» E. | |
| 8263. |
What is typical bandwidths of a 2-wire telephone line? |
| A. | 300 Hz to 3.4 kHz |
| B. | 20 Hz to 4 kHz |
| C. | dc to 4 kHz |
| D. | 20 Hz to 20 kHz |
| Answer» B. 20 Hz to 4 kHz | |
| 8264. |
Modulation index of a AM wave is measured using oscilloscope. The display on the CRO is as shown in figure it can be concluded that |
| A. | the output wave is distorted |
| B. | the output wave is under modulated |
| C. | the modulation index is 100% |
| D. | the modulation index is 50% |
| Answer» B. the output wave is under modulated | |
| 8265. |
The sampling frequency in CD is 10 kHz. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8266. |
Vestigial sideband is most commonly used in |
| A. | radio transmission |
| B. | television transmission |
| C. | telephony |
| D. | all of the above |
| Answer» C. telephony | |
| 8267. |
Costa's receiver is used for |
| A. | coherent detection of AM-SC signal |
| B. | asynchronous detection of AM-SC signal |
| C. | amplitude modulation of signal |
| D. | frequency modulation of signal |
| Answer» B. asynchronous detection of AM-SC signal | |
| 8268. |
In filter system of sideband suppression the advantage of using mechanical filter is |
| A. | smaller size |
| B. | good bandpass |
| C. | good attenuation characteristics |
| D. | all of the above |
| Answer» E. | |
| 8269. |
Why does a FM radio station perform better than and AM station radiating the same actual power? |
| A. | FM is immune to noise |
| B. | AM has only two sidebands while FM has more |
| C. | FM uses larger bandwidth for large modulation depth. |
| D. | Capture effects appears in FM. |
| Answer» E. | |
| 8270. |
Which of the following is invariably found in SSB? |
| A. | Tuned modulator |
| B. | Class B, RF amplifier |
| C. | Class C, audio amplifier |
| D. | All of the above |
| Answer» B. Class B, RF amplifier | |
| 8271. |
An amplifier of passband 450 kHz to 460 kHz will be named as |
| A. | video amplifier |
| B. | audio frequency amplifier |
| C. | tuned voltage amplifier |
| D. | wideband amplifier |
| Answer» D. wideband amplifier | |
| 8272. |
In cable TV local programmes can be telecast at any frequency. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8273. |
In VHS format the width of tape is |
| A. | 2" |
| B. | 1" |
| C. | 1/2" |
| D. | 1/4" |
| Answer» D. 1/4" | |
| 8274. |
If B is channel bandwidth, S is signal power and N is the total noise within the channel bandwidth, the channel capacity C of a white band limited gaussian channel is |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/516-469-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/516-469-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/516-469-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/516-469-4.png"> |
| Answer» B. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/516-469-2.png"> | |
| 8275. |
In the spectrum of a frequency modulated wave |
| A. | carrier frequency cannot disappear |
| B. | carrier frequency vanishes when modulation index is large |
| C. | the number of significant sidebands depends upon modulation index |
| D. | none of the above |
| Answer» D. none of the above | |
| 8276. |
Which of the following statement is false? |
| A. | A stationary process is always a ergodic process |
| B. | A ergodic process is always a stationary random process |
| C. | It is possible to have a stationary random |
| D. | None of the above |
| Answer» C. It is possible to have a stationary random | |
| 8277. |
If the transmitted pulse power of a radar is Pt (peak value) and the antenna is isotropic, the power density at a distance r is |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/524-657-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/524-657-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/524-657-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/524-657-4.png"> |
| Answer» C. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/524-657-3.png"> | |
| 8278. |
In a wave the electric field lines are vertical. Then the wave is |
| A. | horizontally polarized |
| B. | vertically polarized |
| C. | either (a) or (b) |
| D. | neither (a) nor (b) |
| Answer» C. either (a) or (b) | |
| 8279. |
For broadcasting purpose, full AM signal is preferred to SSB signal because |
| A. | it requires large bandwidth |
| B. | generation of full AM is easier |
| C. | detection of full AM is simpler |
| D. | none of the above |
| Answer» C. detection of full AM is simpler | |
| 8280. |
The difference between phase and frequency modulation |
| A. | is purely of academic interest |
| B. | lies in the different definitions of the modulation index |
| C. | lies in the poor audio response of phase modulation |
| D. | is too great to make the two systems compatible |
| Answer» C. lies in the poor audio response of phase modulation | |
| 8281. |
The percentage saving in power when the carrier and one of the sidebands are suppressed in an AM wave modulated to a depth of 100% will be nearly |
| A. | 50% |
| B. | 66% |
| C. | 75% |
| D. | 83% |
| Answer» E. | |
| 8282. |
Over which frequency range the effect of atmospheric noise is significant? |
| A. | Over 35 MHz |
| B. | Below 30 MHz |
| C. | Between 30 MHz and 100 MHz |
| D. | Between 100 MHz and 150 MHz |
| Answer» E. | |
| 8283. |
The baud rate is |
| A. | not equal to signalling rate |
| B. | always equal to bit transfer rate |
| C. | equal to twice the bandwidth of an ideal channel |
| D. | equal to half the bandwidth of ideal channel |
| Answer» D. equal to half the bandwidth of ideal channel | |
| 8284. |
An oscillator at 4.2 MHz is followed by two frequency doublers and two triplers. The output frequency will be |
| A. | 84 MHz |
| B. | 112.4 MHz |
| C. | 151.2 MHz |
| D. | 303.4 MHz |
| Answer» D. 303.4 MHz | |
| 8285. |
If is the frequency of modulating voltage in FM, the modulation index is proportional to |
| A. | |
| B. | 1/ |
| C. | <span class="root"> </span> |
| D. | 1/ |
| E. | <span class="root"> </span> |
| Answer» C. <span class="root"> </span> | |
| 8286. |
Which camera tube has gamma of almost unity? |
| A. | Vidicon |
| B. | Plumbicon |
| C. | New vicon |
| D. | Saticon |
| Answer» E. | |
| 8287. |
When satellite radio beam is aimed towards earth, it illuminates on the earth for an oval shaped area called |
| A. | foot print |
| B. | beam area |
| C. | satellite service area |
| D. | radiated area |
| Answer» B. beam area | |
| 8288. |
FM broadcast is used in |
| A. | VHP range |
| B. | UHF range |
| C. | MF range |
| D. | both VHP and UHF range |
| Answer» E. | |
| 8289. |
The power requirement of a RADAR used in military operations is |
| A. | a few watts |
| B. | about 500 W |
| C. | about 2000 W |
| D. | a few megawatts |
| Answer» E. | |
| 8290. |
Which of the following microphones has maximum distortion? |
| A. | Ribbon |
| B. | Condenser |
| C. | Crystal |
| D. | Carbon |
| Answer» E. | |
| 8291. |
In tape recorder erase head is active during recording. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8292. |
In an AM system, doubling of modulation index doubles the antenna current. The system is |
| A. | single side band full carrier |
| B. | vestigial side band |
| C. | single side band suppressed carrier |
| D. | double side band full carrier |
| Answer» D. double side band full carrier | |
| 8293. |
Which is not purpose of modulation? |
| A. | Effective radiation |
| B. | Multiplexing |
| C. | Narrow band |
| D. | Increase in signal power |
| Answer» E. | |
| 8294. |
Which of the following can provide two or more voice circuits with the same carrier? |
| A. | SSB |
| B. | Carrier reinsertion |
| C. | Lincompex |
| D. | Independent side band system |
| Answer» C. Lincompex | |
| 8295. |
In FM and AM the ratio of signal to noise ratio at the detector output least depends upon |
| A. | bandwidth |
| B. | transmission |
| C. | carrier frequency |
| D. | modulating frequency |
| Answer» D. modulating frequency | |
| 8296. |
A linear diode detector uses RC filter. As modulation index increases the maximum permissible value of time constant RC |
| A. | increases |
| B. | decreases |
| C. | remains constant |
| D. | either (a) or (c) |
| Answer» C. remains constant | |
| 8297. |
The noise generated by a resistor depends upon |
| A. | its operating temperature |
| B. | its resistance value |
| C. | both (a) and (b) |
| D. | bandwidth |
| Answer» C. both (a) and (b) | |
| 8298. |
Coupling and bypass filters can be a source of |
| A. | low-frequency parasitics |
| B. | high-frequency parasitics |
| C. | carrier frequency parasitics |
| D. | none of the above |
| Answer» C. carrier frequency parasitics | |
| 8299. |
Assertion (A): SSB transmitter is generally smaller than AM transmitter Reason (R): SSB systems mostly use combined transmitter receiver. |
| 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» E. | |
| 8300. |
The VLF, LF and MF antennas are |
| A. | horizontally polarized |
| B. | vertically polarized |
| C. | non linearly polarized |
| D. | either (a) or (b) |
| Answer» C. non linearly polarized | |