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.
| 8501. |
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. | |
| 8502. |
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"> | |
| 8503. |
In VCR, the chrominance signal's frequency is |
| A. | up converted during recording and down converted during playback |
| B. | down converted during recording and up converted during playback |
| C. | not changed during recording and playback |
| D. | any of the above depending on VCR system |
| Answer» C. not changed during recording and playback | |
| 8504. |
ARQ stands for |
| A. | Automatic Repeat Quest |
| B. | Analog Repeat Request |
| C. | Automatic Repeat Request |
| D. | None Of the above |
| Answer» D. None Of the above | |
| 8505. |
Tuned voltage amplifiers are not used |
| A. | in public address systems |
| B. | in radio receivers |
| C. | in television receivers for sound signals |
| D. | in television receivers for video signals |
| Answer» B. in radio receivers | |
| 8506. |
MTSO stands for |
| A. | Metropolitan Telecommunication Subscribers Office |
| B. | Metropolitan Telecommunication Switching Office |
| C. | Mobile Telecommunication Switching Office |
| D. | Mobile Telecommunication Subscriber Office |
| Answer» D. Mobile Telecommunication Subscriber Office | |
| 8507. |
The main advantage of TDM over FDM is that it |
| A. | needs less power |
| B. | needs less bandwidth |
| C. | needs simple circuitry |
| D. | gives better S/N ratio |
| Answer» D. gives better S/N ratio | |
| 8508. |
Which of the following is very useful as multiband HF receiving antenna? |
| A. | Square loop |
| B. | Conical horn |
| C. | Folded dipole |
| D. | Log-periodic |
| Answer» E. | |
| 8509. |
VLF waves are sometimes used because |
| A. | they penetrate the ionosphere easily |
| B. | they are very reliable |
| C. | they require low power |
| D. | they require transmitting antennas of convenient sizes |
| Answer» C. they require low power | |
| 8510. |
An MTI compares a set of received echos with those received during the previous sweep. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8511. |
If e = 10 sin(108 t + 3 sin 104 t) then the deviation is |
| A. | 4.77 kHz |
| B. | 47.7 kHz |
| C. | 477 kHz |
| D. | 4770 kHz |
| Answer» C. 477 kHz | |
| 8512. |
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 | |
| 8513. |
How much is contributed by each bit in the code word of a PCM system under uniform and symmetric quantization to the signal to noise ratio? |
| A. | 3 dB |
| B. | 4 dB |
| C. | 5 dB |
| D. | 6 dB |
| Answer» E. | |
| 8514. |
Noise which assumes great importance at high frequencies is |
| A. | flicker noise |
| B. | Johnson noise |
| C. | transit-time noise |
| D. | shot noise |
| Answer» D. shot noise | |
| 8515. |
Which one is Analog Continuous modulation technique? |
| A. | AM |
| B. | DM |
| C. | PAM |
| D. | PCM |
| Answer» B. DM | |
| 8516. |
AM transmitter employing low level modulation |
| A. | uses class C amplifier for amplification |
| B. | requires higher audio power |
| C. | has a poor efficiency |
| D. | has a higher efficiency |
| Answer» D. has a higher efficiency | |
| 8517. |
As the area of a public meeting increases the amplifier power output required increases. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8518. |
In FM, as the modulating frequency decreases and the modulating voltage amplitude |
| A. | increases, the modulation index increases |
| B. | decrease, the modulation index increases |
| C. | remains constant, the modulation index increases |
| D. | remains constant, the modulation index decreases |
| Answer» D. remains constant, the modulation index decreases | |
| 8519. |
The function of duplexer in a RADAR is |
| A. | to permit the use of same antenna for transmission and reception |
| B. | to provide gain to the transmitted power |
| C. | to amplify the received signal |
| D. | both (b) and (c) |
| Answer» B. to provide gain to the transmitted power | |
| 8520. |
In a plate modulated class C amplifier, the peak supply voltage is V. The maximum plate-cathode voltage can be |
| A. | 1 V |
| B. | 1.5 V |
| C. | 2.5 V |
| D. | 4 V |
| Answer» B. 1.5 V | |
| 8521. |
Neper is |
| A. | larger than a decibel |
| B. | smaller than decibel |
| C. | equal to 1 decibel |
| D. | none of the above |
| Answer» B. smaller than decibel | |
| 8522. |
In VHS format width of audio track is |
| A. | 5 mm |
| B. | 2 mm |
| C. | 1 mm |
| D. | 0.1 mm |
| Answer» D. 0.1 mm | |
| 8523. |
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 | |
| 8524. |
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 | |
| 8525. |
The simplest method of suppression of unwanted side band in AM is |
| A. | filter method |
| B. | phase shift method |
| C. | third method |
| D. | both (a) and (b) |
| Answer» B. phase shift method | |
| 8526. |
For attenuation of low frequencies we should use |
| A. | shunt capacitance |
| B. | series capacitance |
| C. | shunt inductance |
| D. | series inductance |
| Answer» C. shunt inductance | |
| 8527. |
Each frequency in the modulating wave gives rise to four side bands. |
| A. | True |
| B. | False |
| Answer» C. | |
| 8528. |
The tape recorders used in homes have |
| A. | common head and common amplifier system for recording and playback |
| B. | different heads and amplifiers for recording and playback |
| C. | same head but different amplifiers for recording and playback |
| D. | different heads but same amplifier for recording and playback |
| Answer» B. different heads and amplifiers for recording and playback | |
| 8529. |
In a communication system, noise is most likely to affect the signal |
| A. | at the receiver |
| B. | at the transmitter |
| C. | at the information source |
| D. | in the channel |
| Answer» E. | |
| 8530. |
Assertion (A): CCIR-B system has 625 scanning lines per frame and 2 : 1 interlace.Reason (R): The aspect ratio is 4 : 3 |
| 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 | |
| 8531. |
A transmitter power of 10 W is increased by 30 dB. The effective radiated power is |
| A. | 100 W |
| B. | 1000 W |
| C. | 10000 W |
| D. | 100000 W |
| Answer» D. 100000 W | |
| 8532. |
It is desired to couple a coaxial line to a two parallel wire line. It is best to use |
| A. | quarter wave transformer |
| B. | balun |
| C. | slotted line |
| D. | directional coupler |
| Answer» C. slotted line | |
| 8533. |
24 telephone channels are frequency division multiplexed using an SSB modulation. Assuming 3 kHz per channel, the required band width is |
| A. | 8 kHz |
| B. | 27 kHz |
| C. | 21 kHz |
| D. | 72 kHz |
| Answer» E. | |
| 8534. |
If sound intensity is 8 W/m2, the dB level of this sound is about |
| A. | 5 dB |
| B. | 50 dB |
| C. | 129 dB |
| D. | 1290 dB |
| Answer» D. 1290 dB | |
| 8535. |
The distance of a direct broadcasting satellite from earth's surface is about |
| A. | 1000 km |
| B. | 10000 km |
| C. | 36000 km |
| D. | 55000 km |
| Answer» D. 55000 km | |
| 8536. |
UHF range is |
| A. | 3 to 30 MHz |
| B. | 30 to 300 MHz |
| C. | 300 to 3000 MHz |
| D. | 3000 to 30000 MHz |
| Answer» D. 3000 to 30000 MHz | |
| 8537. |
Which of the following microphones has an inbuilt amplifier? |
| A. | Condenser |
| B. | Moving coil |
| C. | Ribbon |
| D. | Carbon |
| Answer» B. Moving coil | |
| 8538. |
In a satellite system circular polarization is to be obtained. The antenna used is |
| A. | parabolic |
| B. | horn |
| C. | log periodic |
| D. | helical |
| Answer» E. | |
| 8539. |
As the magnitude of reverse bias is increased, the capacitance of varactor diode |
| A. | increases |
| B. | decreases |
| C. | first increase, then decreases |
| D. | first decreases then increases |
| Answer» C. first increase, then decreases | |
| 8540. |
A horizontal output stage is cutoff for retrace and 40% of trace. If time for each horizontal line is 64 s and retrace time is 12 s, the transistor is conducting for about |
| A. | 64 s |
| B. | 6.4 s |
| C. | 31 s |
| D. | 3.1 s |
| Answer» D. 3.1 s | |
| 8541. |
A TV remote control works on the principle of |
| A. | pulse code modulated ultra violet light |
| B. | pulse code modulated infrared light |
| C. | demodulation |
| D. | either (a) or (b) |
| Answer» C. demodulation | |
| 8542. |
To prevent overloading in the last IF amplifier one should use |
| A. | variable sensitivity |
| B. | squelch |
| C. | double conversion |
| D. | variable selectivity |
| Answer» B. squelch | |
| 8543. |
A reflex klystron oscillator is a |
| A. | low power device |
| B. | high power device |
| C. | high efficiency device |
| D. | both (a) and (b) |
| Answer» B. high power device | |
| 8544. |
Assertion (A): Impedance measurement at microwave frequencies is done by finding SWR.Reason (R): SWR and reflection coefficient depend on the characteristic impedance and load impedance. |
| 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 | |
| 8545. |
Consider the following applications TV tuningActive filterMicrowave frequency multiplication In which of above can a varactor diode be used? |
| A. | 1 2 and 3 |
| B. | l and 2 only |
| C. | 1 and 3 only |
| D. | 2 and 3 only |
| Answer» B. l and 2 only | |
| 8546. |
Assertion (A): PIN diode is used as a fast switch.Reason (R): PIN diode has very high resistance when reverse biased and very low resistance when forward biased. |
| 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 | |
| 8547. |
A pulsed radar produces 1 sec pulses at a rate of 1000 per second. The duty cycle is |
| A. | 0.001 |
| B. | 0.01 |
| C. | 0.1 |
| D. | 1 |
| Answer» B. 0.01 | |
| 8548. |
When a line is loaded the characteristic impedance is equal to |
| A. | <span class="root">(R + <i>j</i> L)(G + <i>j</i> C)</span> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/09-30-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/09-30-3.png"> |
| D. | <span class="root">LC</span> |
| Answer» C. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/09-30-3.png"> | |
| 8549. |
If the plate supply voltage for a plate modulated class C amplifier is E, the maximum plate cathode voltage could be almost as high as |
| A. | E |
| B. | 2 E |
| C. | 3 E |
| D. | 4 E |
| Answer» D. 4 E | |
| 8550. |
In a radio receiver with simple AGC |
| A. | the highest AGC voltage is produced between stations |
| B. | an increase in signal strength produces more AGC |
| C. | the audio stage gain is normally controlled by AGC |
| D. | the faster the time constant of AGC, more accurate the output |
| Answer» C. the audio stage gain is normally controlled by AGC | |