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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.
| 251. |
The direction of rotation of a CD is |
| A. | clockwise |
| B. | anticlockwise |
| C. | clockwise or anticlockwise depending on frequency of data stored |
| D. | mostly anticlockwise but some times clockwise |
| Answer» C. clockwise or anticlockwise depending on frequency of data stored | |
| 252. |
Assertion (A): Data communication using digital data must be very accurate.Reason (R): In analog signals redundancy is available but in digital signals redundancy is not available. |
| A. | A is correct but R is wrong |
| B. | A is wrong but R is correct |
| Answer» B. A is wrong but R is correct | |
| 253. |
A p matching network for coupling the transmitter output of the antenna is shown in figure. In this C2 should be tuned for |
| A. | minimum D.C. plate current |
| B. | maximum D.C. plate current |
| C. | maximum RF antenna current |
| D. | specified value of the D.C. plate current |
| Answer» C. maximum RF antenna current | |
| 254. |
The diameter and thickness of CD are |
| A. | 6 cm and 1.2 mm |
| B. | 6 cm and 0.6 mm |
| C. | 12 cm and 0.6 mm |
| D. | 12 cm and 1.2 mm |
| Answer» D. 12 cm and 1.2 mm | |
| 255. |
The EHT voltage in a picture tube of TV is |
| A. | about 1000 kV |
| B. | about 100 kV |
| C. | about 15 kV |
| D. | about 1 kV |
| Answer» D. about 1 kV | |
| 256. |
Assertion (A): A balun is an RF impedance matching transformer. Reason (R): Sometimes a booster amplifier is used with a TV set. |
| 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 | |
| 257. |
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 | |
| 258. |
For low impedance SAW filter the most suitable material for substrate of SAW filter is |
| A. | Lithium titanate |
| B. | Lithium neobate |
| Answer» B. Lithium neobate | |
| 259. |
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 | |
| 260. |
In TV transmitter, the function of duplexer is |
| A. | to amplify video signal |
| B. | to remove distortions in audio signal |
| C. | to combine outputs of visual and audio transmitters |
| D. | to amplify audio signal |
| Answer» D. to amplify audio signal | |
| 261. |
To ensure good transient response in audio systems the natural frequencies should be |
| A. | above 40 Hz and below 15 kHz |
| B. | above 40 Hz |
| C. | above 15 kHz |
| D. | below 40 Hz and above 15 kHz |
| Answer» D. below 40 Hz and above 15 kHz | |
| 262. |
The saving of power in DSB-SC modulated at 80% is |
| A. | NIL |
| B. | 0.8 |
| C. | 0.7576 |
| D. | 0.5 |
| Answer» D. 0.5 | |
| 263. |
The RF section of a radio transmit generally consists of |
| A. | master oscillator |
| B. | final power amplifier to feed antenna |
| C. | buffer stage |
| D. | all of the above |
| Answer» E. | |
| 264. |
Audio and video signals are called modulating waves. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 265. |
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 | |
| 266. |
PCM : Quantising Noise :: Transistor : |
| A. | Partition noise |
| B. | Shot noise |
| C. | Whirl |
| D. | No noise |
| Answer» B. Shot noise | |
| 267. |
Trap circuits used in video IF amplifier of colour TV are |
| A. | High Q, LC resonant circuit |
| B. | Low Q, LC resonant circuit |
| C. | High Q, RLC resonant circuit |
| D. | Low Q, RLC resonant circuit |
| Answer» B. Low Q, LC resonant circuit | |
| 268. |
In a Vidicon camera tube, the beam current is controlled by |
| A. | grid G1 |
| B. | grid G2 |
| C. | grids G1, G2, G3 |
| D. | grid G2, G3 |
| Answer» B. grid G2 | |
| 269. |
In the above case if the modulating frequency is increased to 20 kHz the bandwidth will be |
| A. | 0.05 MHz |
| B. | 1 MHz |
| C. | 2 MHz |
| D. | 4 MHz |
| Answer» D. 4 MHz | |
| 270. |
Which one the following is an advantage of AM over FM? |
| A. | FM has wide bandwidth |
| B. | FM has better |
| C. | FM is more immune to noise |
| D. | Probability of noise spike generation is less in AM |
| Answer» E. | |
| 271. |
Assertion (A): A colour TV uses a SAW filter to give stable band pass response and high gain.Reason (R): Devices using SAW principle are used in many systems. |
| 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 | |
| 272. |
Pulse stuffing is used in |
| A. | synchronous TDM |
| B. | asynchronous TDM |
| C. | Any TDM |
| D. | All |
| Answer» C. Any TDM | |
| 273. |
Directivity means |
| A. | minimum directive gain |
| B. | none of the above |
| Answer» B. none of the above | |
| 274. |
If each frequency component of f(t) is shifted by p/2, the resulting signal is |
| A. | Hilbert transform of f(t) |
| B. | Inverse Hilbert transform of f(t) |
| C. | Laplace transform of f(t) |
| D. | Fourier transform of f(t) |
| Answer» B. Inverse Hilbert transform of f(t) | |
| 275. |
Which of the following amplifiers has a voltage gain of less than 1? |
| A. | CB |
| B. | CE or CB |
| Answer» C. | |
| 276. |
De-emphasis circuit is used |
| A. | to attenuate high frequencies |
| B. | to attenuate low frequencies |
| C. | to attenuate mid-band frequencies |
| D. | None of the above |
| Answer» B. to attenuate low frequencies | |
| 277. |
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 | |
| 278. |
In a cellular communication system, path loss between transmitter and receiver is due to |
| A. | scattering from building, trees, vehicles and other structure |
| B. | reason at (a) above and due to reflections from ground only |
| C. | reason at (a) and (b) above along with reflections from ionosphere only |
| D. | reasons at (a), (b) and (c) above along with loss due to surface wave phenomenon |
| Answer» C. reason at (a) and (b) above along with reflections from ionosphere only | |
| 279. |
For 10 bit PCM system, the signal to quantization noise ratio is 62 dB. If the number of bits is increased by 2, then the signal to quantization noise ratio will |
| A. | increased by 6 dB |
| B. | increased by 12 dB |
| C. | decreased by 6 dB |
| D. | decreased by 12 dB |
| Answer» C. decreased by 6 dB | |
| 280. |
As the area of a public meeting increases the amplifier power output required increases. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 281. |
As regards BCH code, Hamming code and Reed-Solomon code |
| A. | BCH and Reed-Solomon code are special case of Hamming code |
| B. | none of the above |
| Answer» C. | |
| 282. |
Some possible functions of AGC in a TV receiver are To increase gain for weak signalsTo decrease gain for strong signalsTo change the contrast when we switch from one channel to otherTo reduce flutter Which of the above are correct? |
| A. | 1, 2, 3 |
| B. | 2, 3, 4 |
| Answer» C. | |
| 283. |
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 | |
| 284. |
The gap width in audio heads is about 0.01 mm. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 285. |
A helical antenna is used for satellite tracking due to its |
| A. | circular polarization |
| B. | both (a) and (b) |
| Answer» B. both (a) and (b) | |
| 286. |
If frames are repeated at 60 Hz and each frame has 525 lines, the time for scanning one horizontal line (for progressive scanning and no interlacing) is about |
| A. | 320 μs |
| B. | 32 μs |
| C. | 3.2 μs |
| D. | 0.32 μs |
| Answer» C. 3.2 Œºs | |
| 287. |
By the use of which of the following the PPM can be converted to PWM? |
| A. | A stable multivibrator |
| B. | Integrator |
| C. | Monostable multivibrator |
| D. | Bistable Multivibrator |
| Answer» E. | |
| 288. |
A radio station works at 800 kHz and uses AM. If this is a public broadcast system, it should transmit using |
| A. | parabolic reflector to transmit all round |
| B. | turnstile antenna for the required land |
| C. | half wave long horizontal wave |
| D. | a vertical antenna less than quarter for practical reasons |
| Answer» E. | |
| 289. |
The maximum range of a radar is proportional to |
| A. | square root of peak transmitted pulse power |
| B. | fourth root of peak transmitted pulse power |
| C. | peak transmitted pulse power |
| D. | none of the above |
| Answer» C. peak transmitted pulse power | |
| 290. |
In TV scanning sequence of lines is |
| A. | left to right |
| B. | right to left |
| C. | left to right for odd fields and right to left for even field |
| D. | left to right for even fields and right to left for odd field |
| Answer» B. right to left | |
| 291. |
Assertion (A): Bandwidth of a TV signal is 5 MHz.Reason (R): TV systems use vestigial side band transmission. |
| 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 | |
| 292. |
Which is not purpose of modulation? |
| A. | Effective radiation |
| B. | Multiplexing |
| C. | Narrow band |
| D. | Increase in signal power |
| Answer» E. | |
| 293. |
Pre-emphasis and De-emphasis is done by using R-C circuit. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 294. |
Colour picture tube needs higher anode voltage and needs larger beam and cathode currents than monochrome tube because |
| A. | it is bigger in size |
| B. | it has higher level of illumination |
| C. | the tube has to illuminate three phosphors simultaneously |
| D. | the tube has lower efficiency because of aperture mask |
| Answer» E. | |
| 295. |
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 | |
| 296. |
In a colour TV receiver AFT stands for |
| A. | Automatic Fine Tuning |
| B. | Automatic Frequency Tuning |
| C. | Automatic Field Tuning |
| D. | Alignment Frequency Tuning |
| Answer» B. Automatic Frequency Tuning | |
| 297. |
An angle modulated signal is given by s(t) = cos 2p (2 x 106t + 30 sin 150t + 40 cos 150t). The maximum frequency and phase deviations of s(t) are |
| A. | 10.5 kHz, 140p rad |
| B. | 6 kHz and 80p rad |
| C. | 10.5 kHz, 100p rad |
| D. | 7.5 kHz, 100p rad |
| Answer» E. | |
| 298. |
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. | |
| 299. |
The reactance of coupling capacitor for AC signals in an amplifier, should be |
| A. | as low as possible |
| B. | as high as possible |
| C. | neither low nor high |
| D. | either low or high |
| Answer» B. as high as possible | |
| 300. |
Which one of the following gives maximum probability of error? |
| A. | ASK |
| B. | DPSK |
| C. | FSK |
| D. | PSK |
| Answer» B. DPSK | |