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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.
| 8451. |
Which of the following is a better recording medium? |
| A. | Ferric oxide |
| B. | Ferrous oxide |
| C. | Chromium di oxide |
| D. | Either (a) or (b) |
| Answer» D. Either (a) or (b) | |
| 8452. |
The number of possible colours with a 4 line digital input monitor are |
| A. | 4 |
| B. | 16 |
| C. | 64 |
| D. | 2 |
| Answer» C. 64 | |
| 8453. |
In a 100% amplitude modulated signal, the power in the upper sideband when carrier power is to be 100 W and modulation system SSBSC, is |
| A. | 100 W |
| B. | 66 W |
| C. | 50 W |
| D. | 25 W |
| Answer» E. | |
| 8454. |
Which is a digital coding technique? |
| A. | PCM |
| B. | DM |
| C. | DPCM |
| D. | All |
| Answer» E. | |
| 8455. |
In a two stage cascade amplifier the equivalent noise temperatures are Te1 and Te2. If the gains of the two stages are G1 and G2, the overall noise temperature Te is |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/505-231-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/505-231-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/505-231-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/505-231-4.png"> |
| Answer» D. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/505-231-4.png"> | |
| 8456. |
The modulation index of a narrowband FM signal is |
| A. | nearly equal to 0.3 |
| B. | much less than unity |
| C. | nearly 0.5 |
| D. | much more than unity |
| Answer» B. much less than unity | |
| 8457. |
Which of the following noise sources is different from others? |
| A. | Cosmic |
| B. | Solar |
| C. | Atmospheric |
| D. | Galactic |
| Answer» D. Galactic | |
| 8458. |
For the transmission of normal speech, the PCM channel needs a bandwidth of __________ kHz. |
| A. | 2 |
| B. | 4 |
| C. | 16 |
| D. | 32 |
| Answer» C. 16 | |
| 8459. |
In a low level amplitude modulated system, the amplifier modulated stage must be |
| A. | class C |
| B. | linear |
| C. | non linear |
| D. | harmonic |
| Answer» C. non linear | |
| 8460. |
A noise can be represented as superposition of spectral components. When this noise is passed through a narrow band filter, the output of filter should look like |
| A. | sinusoidal |
| B. | rectangular |
| C. | triangular |
| D. | none of the above |
| Answer» B. rectangular | |
| 8461. |
A narrow band noise show |
| A. | AM only |
| B. | AM and FM |
| C. | FM |
| D. | PCM |
| Answer» C. FM | |
| 8462. |
The upper and lower side frequencies for 3 kHz audio modulation with a 27 MHz carrier frequency will be |
| A. | 30 and 24 MHz |
| B. | 27.3 and 26.7 MHz |
| C. | 27.3 and 26.97 MHz |
| D. | 27.3 and 26.97 MHz |
| Answer» C. 27.3 and 26.97 MHz | |
| 8463. |
Consider the following advantages of phase array radar simple circuitryability to track and scan simultaneouslyability to track many targets togethervery fast scanning Which of the above are correct? |
| A. | 1, 2, 3 |
| B. | 1, 3, 4 |
| C. | 2, 3, 4 |
| D. | 1, 4 only |
| Answer» D. 1, 4 only | |
| 8464. |
For demodulating PCM; it is first converted into |
| A. | PDM |
| B. | PPM |
| C. | PWM |
| D. | PAM |
| Answer» E. | |
| 8465. |
In an AM transmitter after the modulation stage, class C amplifier |
| A. | can be used |
| B. | cannot be used |
| C. | may be used, but it has no use |
| D. | can't be determine to use |
| Answer» C. may be used, but it has no use | |
| 8466. |
The maximum number of AM broadcast stations that can be accommodated in a 100 kHz bandwidth for the highest modulating frequency of 5 kHz will be |
| A. | 100 |
| B. | 20 |
| C. | 10 |
| D. | 1 |
| Answer» D. 1 | |
| 8467. |
One of the advantages of base modulation over collector modulation in a class C transistor amplifier is |
| A. | higher efficiency |
| B. | more linear operation |
| C. | more power output per transistor |
| D. | lesser requirement of modulating power |
| Answer» E. | |
| 8468. |
The spectrum of the white noise and an impulse function is similar in following aspects |
| A. | both have similar magnitude spectrum |
| B. | both have similar magnitude and Phase spectrum |
| C. | no relation |
| D. | similar phase spectrum |
| Answer» B. both have similar magnitude and Phase spectrum | |
| 8469. |
In a telephone system, the grade of service means |
| A. | the quality of sound reception at the receiver telephone |
| B. | the probability that a called for connection is established |
| C. | the type of wires cables used for the system |
| D. | none of the above |
| Answer» C. the type of wires cables used for the system | |
| 8470. |
For a short dipole having an effective length less than half the wavelength the radiation resistance is |
| A. | proportional to length |
| B. | proportional to square root of length |
| C. | proportional to square of length |
| D. | none of the above |
| Answer» B. proportional to square root of length | |
| 8471. |
A longwave AM broadcast transmitter needs |
| A. | very small carrier power |
| B. | very large carrier power |
| C. | small carrier power |
| D. | large carrier power |
| Answer» C. small carrier power | |
| 8472. |
The highest modulation frequencies typically used in FM broadcast is |
| A. | 5 kHz |
| B. | 10 kHz |
| C. | 15 kHz |
| D. | 25 kHz |
| Answer» D. 25 kHz | |
| 8473. |
AGC voltage is applied to the stages which are |
| A. | before the detector stage |
| B. | after the detector stage |
| C. | either before or after the detector stage |
| D. | none of the above |
| Answer» B. after the detector stage | |
| 8474. |
Modulation system used for video-modulation in television broadcast is |
| A. | SSB AM with carrier |
| B. | SSB with carrier suppressed |
| C. | DSB AM with carrier |
| D. | a modified form of SSB with carrier called vestigial sideband |
| Answer» E. | |
| 8475. |
LCD uses |
| A. | nematic crystals |
| B. | sematic crystals |
| C. | cholesteric crystals |
| D. | twisted nematic crystal |
| Answer» E. | |
| 8476. |
The intermediate frequency of a superheterodyne receiver is 450 kHz. If it is tuned to 1200 kHz, the image frequency will be |
| A. | 750 kHz |
| B. | 900 kHz |
| C. | 1600 kHz |
| D. | 2100 kHz |
| Answer» E. | |
| 8477. |
In the above case the modulation index will be |
| A. | 9.6 |
| B. | 28.8 |
| C. | 57.6 |
| D. | 100 |
| Answer» E. | |
| 8478. |
Which of the following statement regarding single-sideband (SSB) transmission is not correct? |
| A. | In such transmission only or sideband is transmitted, leaving of the other sideband and the carrier |
| B. | It has gained general acceptance of use in home-entertainment equipment |
| C. | It is generally reserved for point-to-point communication |
| D. | The amount of power and bandwidth necessary to be transmitted for a given amount of information are appreciable reduced |
| Answer» C. It is generally reserved for point-to-point communication | |
| 8479. |
Which of the following stage is not present in AM receiver as compared to FM receiver? |
| A. | AM amplifier |
| B. | Demodulator |
| C. | Amplitude limiter |
| D. | AF amplitude |
| Answer» D. AF amplitude | |
| 8480. |
The number of spectral component when two cosine waves are multiplied of different frequency |
| A. | 1 |
| B. | 2 |
| C. | 8 |
| D. | 4 |
| Answer» E. | |
| 8481. |
Radiation resistance of an antenna is a |
| A. | dc resistance |
| B. | ac resistance |
| C. | either (a) or (b) |
| D. | none of the above |
| Answer» C. either (a) or (b) | |
| 8482. |
A 1 MHz sinusoidal carrier is amplitude modulated by a symmetrical square wave of period 100 sec. Which of the following frequencies will not be in the modulated signal? |
| A. | 990 kHz |
| B. | 1010 kHz |
| C. | 1020 kHz |
| D. | 1030 kHz |
| Answer» D. 1030 kHz | |
| 8483. |
The input to a coherent detector is DSB - SC signal plus noise. The noise at the detector output is |
| A. | in phase component |
| B. | quadrature component |
| C. | zero |
| D. | the envelope |
| Answer» B. quadrature component | |
| 8484. |
All of the output pulses are at full transmitter power for a strong signal in all of the following except |
| A. | PWM |
| B. | PAM |
| C. | PFM |
| D. | PCM |
| Answer» C. PFM | |
| 8485. |
The smallest change in sound intensity that can be detected by human ear is __________ dB. |
| A. | 1 |
| B. | 3 |
| C. | 10 |
| D. | 20 |
| Answer» C. 10 | |
| 8486. |
Low frequency boost can be easily compensated by |
| A. | attenuating the frequencies from 0 to 1.25 MHz |
| B. | using an appropriate de-emphasis circuit in the receiver |
| C. | using an appropriate pre-emphasis circuit in the transmitter |
| D. | none |
| Answer» B. using an appropriate de-emphasis circuit in the receiver | |
| 8487. |
In grid bias modulation system the power required for modulating amplifier |
| A. | is negligibly low since grid is negative |
| B. | is large as compared to that for plate modulation |
| C. | is almost the same as compared with plate modulation |
| D. | is small as compared to that for plate modulation |
| Answer» E. | |
| 8488. |
In spread spectrum technique |
| A. | a modulated signal is modulated again |
| B. | a modulated signal is modulated twice again |
| C. | the power of a modulated signal is increased |
| D. | the noise component of a modulated signal is decreased |
| Answer» E. | |
| 8489. |
QAM stands for |
| A. | Quasi-Amplitude Modulation |
| B. | Quadrature Angle Modulation |
| C. | Quadrature Amplitude Modulation |
| D. | None of the above |
| Answer» D. None of the above | |
| 8490. |
Assertion (A): A video monitor does not need RF tuner and IF amplifier Reason (R): The picture tube in TV is basically a CRT. |
| 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 | |
| 8491. |
Consider the following statements as regards IF in radio receivers If IF is too high, poor selectivity and poor adjacent channel rejection could resultIf IF is high, tracking difficulties increaseA very low IF makes selectivity too sharpAs IF is decreased, image frequency rejection becomes better Which of the above are correct? |
| A. | 1, 2, 3, 4 |
| B. | 1, 2, 3 |
| C. | 2, 3, 4 |
| D. | 1, 3, 4 |
| Answer» C. 2, 3, 4 | |
| 8492. |
Audio-signal modulates a 125 MHz carrier, causing a frequency deviation of 5 kHz. The bandwidth of the narrowband FM signal is __________ kHz. |
| A. | 10 |
| B. | 8 |
| C. | 9 |
| D. | 20 |
| Answer» D. 20 | |
| 8493. |
Assertion (A): Radar gave birth to microwave technology.Reason (R): In radar systems very high frequencies give the most accurate results. |
| 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 | |
| 8494. |
In FM noise can be decreased by a feature that AM does not have |
| A. | increasing deviation |
| B. | decreasing deviation |
| C. | reducing modulation index |
| D. | increasing modulation index |
| Answer» D. increasing modulation index | |
| 8495. |
In case of stabilized reactance modulator AFC system |
| A. | phase modulator is converted into frequency modulation by equalizer circuit |
| B. | the discriminator must have a fast time constant to provide demodulation |
| C. | the higher discriminator frequency, the better oscillator frequency |
| D. | the discriminator frequency must be too low, or the system will fail |
| Answer» D. the discriminator frequency must be too low, or the system will fail | |
| 8496. |
A channel has a SNR of 7 and BW 4 kHz. Keeping the channel capacity (BPS) same, the BW is reduced to accommodate more channels. The SNR |
| A. | decreases |
| B. | increases |
| C. | remains same |
| D. | partially affected |
| Answer» C. remains same | |
| 8497. |
The PDF of a Gaussian random variable X is given by . The probability of the event {X = 4} is |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/56-3.94-2.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/534-920-2.png"> |
| C. | 0 |
| D. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/56-3.94-3.png"> |
| Answer» C. 0 | |
| 8498. |
Assertion (A): Demodulation of SSB and AM signals is exactly similar Reason (R): The basic SSB demodulation device is product detector. |
| 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. | |
| 8499. |
In shot noise |
| A. | the current rises around mean value |
| B. | the current rises to peak value, decreases to zero and then again rises |
| C. | the current may become negative |
| D. | the current is always less than the mean value |
| Answer» E. | |
| 8500. |
If Vs is signal voltage, Vn is noise voltage, signal to noise ratio S/N is defined as |
| A. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/512-383-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/512-383-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/512-383-3.png"> |
| D. | none of the above |
| Answer» C. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/512-383-3.png"> | |