MCQOPTIONS
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MCQOPTIONS
This section includes 1362 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 601. |
Assertion (A): In AM, use of SSB reduces the power and bandwidth requirementReason (R): A balanced modulator produces AM with carrier suppressed |
| 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 | |
| 602. |
Since noise phase modulated FM wave, as the noise sideband frequency approaches the carrier frequency, the noise amplitude |
| A. | is equalized |
| B. | is increased |
| C. | is decreased |
| D. | remains constant |
| Answer» D. remains constant | |
| 603. |
An amplifier operating over a frequency range of 18 to 20 MHz has 10 kΩ input resistance. At a temperature of 27° C, the noise voltage at input of amplifier is (Boltzman constant k = 1.38 x 10-23 J/K) |
| A. | 18.2 μV |
| B. | 182 μV |
| C. | 16.2 μV |
| D. | 162 μV |
| Answer» B. 182 ŒºV | |
| 604. |
Present day stereophonic systems have |
| A. | only CD playback facility |
| B. | only tape playback facility |
| C. | both CD and tape playback facilities along with radio |
| D. | none of the above |
| Answer» D. none of the above | |
| 605. |
In a colour TV receiver SAW filter consists of |
| A. | piezoelectric substrate on which are deposited two inter, digital transducers |
| B. | photo conductive substrate which are deposited two inter digital transducers |
| C. | photo voltaic substrate which are deposited two inter digital transducers |
| D. | photo resistive substrate which are deposited two inter digital transducers |
| Answer» B. photo conductive substrate which are deposited two inter digital transducers | |
| 606. |
The simplest mixer circuit for public address system uses |
| A. | fixed resistances |
| B. | variable resistances |
| C. | inductances |
| D. | capacitances |
| Answer» C. inductances | |
| 607. |
In an SSB transmitter one is most likely to find |
| A. | class C audio amplifier |
| B. | tuned modulator |
| C. | class B RF amplifier |
| D. | class AB power amplifier |
| Answer» D. class AB power amplifier | |
| 608. |
Directive gain is |
| A. | a power ratio |
| B. | a voltage ratio |
| C. | a current ratio |
| D. | a distance ratio |
| Answer» B. a voltage ratio | |
| 609. |
In figure (A) and (B) |
| A. | A represents PCM and B represents AM |
| B. | A represents FM and B represents AM |
| C. | A represents AM and B represents FM |
| D. | A represents PCM and B represents FM |
| Answer» D. A represents PCM and B represents FM | |
| 610. |
The line of sight communication requires the transmit and receive antennas to face each other. If the transmit antenna is vertically polarized, for best reception to the receive antenna should be |
| A. | horizontally polarized |
| B. | vertically polarized |
| C. | at 45° within respect to horizontal polarization |
| D. | at 45° with respect to vertical polarization |
| Answer» B. vertically polarized | |
| 611. |
CSSB stands for |
| A. | Compatible Single Sideband |
| B. | Compressed Single Sideband |
| C. | Carrier Single Sideband |
| D. | Coded Single Sideband |
| Answer» B. Compressed Single Sideband | |
| 612. |
Some sources of TV programs are TV cameraTelecineVTRExternal signal Which of the above are actually present in a TV studio? |
| A. | 1, 2, 3 and 4 |
| B. | 1, 2, 3 |
| C. | 1 and 3 |
| D. | 1 2 and 4 |
| Answer» B. 1, 2, 3 | |
| 613. |
Trinitron is a monochrome picture tube. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 614. |
FM is named so because |
| A. | it restrains the frequency excursions of FM |
| B. | it increases the frequency excursions of FM |
| C. | it decreases the amplitude of FM signal |
| D. | it increases the amplitude of FM signal |
| Answer» B. it increases the frequency excursions of FM | |
| 615. |
Which one of the following is analog? |
| A. | PCM |
| B. | PWM |
| C. | Delta modulation |
| D. | Differential PCM |
| Answer» C. Delta modulation | |
| 616. |
In a PCM system, if we increase the quantization levels from 2 to 8, how do the relative bandwidth requirements vary? |
| A. | Get doubled |
| B. | Get tripled |
| C. | Remains same |
| D. | Become eight times |
| Answer» C. Remains same | |
| 617. |
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 | |
| 618. |
In a hi-fi system the frequency response over the audio frequency range should be within |
| A. | ± 10 dB |
| B. | 5 dB |
| C. | 2 dB |
| D. | 1 dB |
| Answer» E. | |
| 619. |
Consider the following functions It detects the AM video carrier IF so as to produce the video signalIt produces and separates out the inter carrier sound IF of 5.5 MHzIt amplifies the video signalIt amplifies the audio signal The video detector in a colour TV performs which of the above functions |
| A. | 1, 2 and 3 |
| B. | 1, 2, 3 and 4 |
| C. | 1 and 2 |
| D. | 1, 2 and 4 |
| Answer» D. 1, 2 and 4 | |
| 620. |
MCVF telegraphy causes |
| A. | SSB techniques |
| B. | pulse modulation |
| C. | Out of bond signalling |
| D. | FM |
| Answer» B. pulse modulation | |
| 621. |
In colour television V and U signals are |
| A. | same as I and Q signal |
| B. | same as R - Y and B - Y |
| C. | modified I and Q signal |
| D. | modified R - Y and B - Y |
| Answer» E. | |
| 622. |
PAM stands for |
| A. | Phase Angle Modulation |
| B. | Phase Amplitude Modulation |
| C. | Pulse Amplitude Modulation |
| D. | Pulse Angle Modulation |
| Answer» D. Pulse Angle Modulation | |
| 623. |
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 | |
| 624. |
Bit is a unit of |
| A. | entropy |
| B. | information |
| C. | channel capacity |
| D. | rate of information |
| Answer» C. channel capacity | |
| 625. |
The maximum permissible distance between two samples of a 2 kHz signal is |
| A. | 1000 μ sec |
| B. | 500 μ sec |
| C. | 250 μ sec |
| D. | 2000 sec |
| Answer» D. 2000 sec | |
| 626. |
In a CD the sampling frequency is nearly |
| A. | half the highest frequency in audio signal |
| B. | equal to highest frequency in audio signal |
| C. | double the highest frequency in audio signal |
| D. | four times the highest frequency in audio signal |
| Answer» D. four times the highest frequency in audio signal | |
| 627. |
Each kilometer of travel in electromagnetic radiation means a time delay of |
| A. | 330 μs |
| B. | 33 μs |
| C. | 3.3 μs |
| D. | 0.33 μs |
| Answer» D. 0.33 Œºs | |
| 628. |
Which of the following microphones has maximum distortion? |
| A. | Ribbon |
| B. | Condenser |
| C. | Crystal |
| D. | Carbon |
| Answer» E. | |
| 629. |
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 | |
| 630. |
It is found that a ship to ship communication suffers from fading. This can be avoided by using |
| A. | space diversity |
| B. | frequency diversity |
| C. | broad band antenna |
| D. | directional antenna |
| Answer» C. broad band antenna | |
| 631. |
Image frequency rejection mainly depends upon |
| A. | detector |
| B. | mixer |
| C. | IF |
| D. | RF |
| Answer» B. mixer | |
| 632. |
When Pc is the unmodulated carrier power and Pt is the total power in the modulated wave, then the maximum power in AM wave is |
| A. | Pt = 1.5 Pc |
| B. | Pt = 2.5 Pc |
| C. | Pt = 2 |
| D. | Pt = 22 Pc |
| Answer» B. Pt = 2.5 Pc | |
| 633. |
Bipolar signalling uses the following bits |
| A. | -1, +1 |
| B. | -1, 0, +1 |
| C. | 0, 1 |
| D. | -1, 0 |
| Answer» C. 0, 1 | |
| 634. |
Filter method and phasing method are the methods for generating |
| A. | SSB signal |
| B. | vestigial side band signal |
| C. | both SSB and vestigial sideband signals |
| D. | none of the above |
| Answer» B. vestigial side band signal | |
| 635. |
Which of the following is a disadvantage of Vestigial Sideband (VSB) system? |
| A. | Low video frequencies are attenuated |
| B. | Bandwidth is conserved resulting in a saving of 2 MHz per channel over DSB system |
| C. | It results in a power boost of two video frequencies |
| D. | It possess the advantages of both DSB and SSB system |
| Answer» D. It possess the advantages of both DSB and SSB system | |
| 636. |
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 | |
| 637. |
At night D layer of ionosphere is absent. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 638. |
Which of the following is true as regards telephone systems? |
| A. | A larger facility carrying a larger load operates less efficiently than a smaller capacity |
| B. | A larger facility carrying a lesser load operates more efficiently than a smaller capacity |
| C. | A larger facility carrying a larger load operates more efficiently than a smaller capacity |
| D. | A smaller capacity carrying a larger load operates more efficiently than a larger capacity |
| Answer» D. A smaller capacity carrying a larger load operates more efficiently than a larger capacity | |
| 639. |
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 | |
| 640. |
A carrier is phase modulated (PM) with frequency deviation of 10 kHz by a single tone frequency of 1 kHz. If the single tone frequency is increased to 2 kHz, assuming that phase deviation remains unchanged, the bandwidth of the PM signal is |
| A. | 21 kHz |
| B. | 22 kHz |
| C. | 42 kHz |
| D. | 44 kHz |
| Answer» E. | |
| 641. |
Assertion (A): Water waves are longitudinal but EM waves are transverseReason (R): In an EM wave electric field, magnetic field and propagation are mutually perpendicular. |
| 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 | |
| 642. |
When a complex signals is used to frequency modulate a carrier, the resulting sideband distribution is |
| A. | symmetrical about the carrier |
| B. | not necessarily symmetrical about the carrier |
| C. | decided by the predominant sidebands |
| D. | none of the above |
| Answer» B. not necessarily symmetrical about the carrier | |
| 643. |
If B is the bandwidth, the thermal noise voltage is proportional to |
| A. | B |
| B. | B0.5 |
| C. | B1.5 |
| D. | B2 |
| Answer» C. B1.5 | |
| 644. |
A 100 + j 100 Ω load is to be matched to a line with Z0 = 300 Ω to give SWR = 1. The reactance of stub is |
| A. | j 200 Ω |
| B. | -j 200 Ω |
| C. | j 100 Ω |
| D. | -j 100 Ω |
| Answer» C. j 100 Œ© | |
| 645. |
The function of a modulator is to |
| A. | separate two frequencies |
| B. | extract information from the carrier |
| C. | amplify the audio frequency signal |
| D. | impress the information on to a RF carrier |
| Answer» E. | |
| 646. |
The reactance of bypass capacitor in a CE amplifier circuit should be |
| A. | equal to the resistance in parallel with it |
| B. | equal to 10% or less of the resistance in parallel with it |
| C. | equal to 50% of the resistance in parallel with it |
| D. | independent of the resistance in parallel with it |
| Answer» C. equal to 50% of the resistance in parallel with it | |
| 647. |
The oscillator frequency is set for |
| A. | best picture |
| B. | max. sound |
| C. | min. sound |
| D. | sound in picture |
| Answer» B. max. sound | |
| 648. |
FM broadcast lies in which band? |
| A. | HF |
| B. | SHF |
| C. | UHF |
| D. | VHF |
| Answer» E. | |
| 649. |
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 | |
| 650. |
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 | |