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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.
| 8551. |
Which one of the following is not necessarily an advantage of the phase cancellation method of obtaining SSB over the filter method? |
| A. | It is possible to generate SSB at any frequency |
| B. | SSB with lower audio frequencies present can be generated |
| C. | Switching from one sideband to other is simpler |
| D. | There are more balanced modulators; therefore the carrier is suppressed better |
| Answer» E. | |
| 8552. |
In an amplitude modulated waveform, the amplitude of the sideband is |
| A. | independent of the carrier amplitude |
| B. | independent of the modulation index |
| C. | carrier amplitude x modulation index |
| D. | 1/2 carrier amplitude x modulation index |
| Answer» E. | |
| 8553. |
Which device has internal positive feedback? |
| A. | Two cavity klystron amplifier |
| B. | Multi-cavity klystron amplifier |
| C. | Reflex klystron amplifier |
| D. | All of the above |
| Answer» D. All of the above | |
| 8554. |
Pulse modulation is used in |
| A. | radio navigation |
| B. | automatic landing equipment |
| C. | data communications |
| D. | all of the above |
| Answer» E. | |
| 8555. |
In communication systems the frequency range used for voice is |
| A. | 15 Hz to 150 Hz |
| B. | 30 Hz to 1000 Hz |
| C. | 100 Hz to 1500 Hz |
| D. | 300 Hz to 3800 Hz |
| Answer» E. | |
| 8556. |
If the carrier of a 100 percent modulated AM wave is suppressed, the percentage power saving will be |
| A. | 50 |
| B. | <img src="/_files/images/electronics-and-communication-engineering/communication-systems/543-1116-1.png"> |
| C. | 100 |
| D. | 150 |
| Answer» B. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/543-1116-1.png"> | |
| 8557. |
Microwave link repeaters are typically 50 km apart in TV transmission due to |
| A. | atmosphere attenuation |
| B. | output power tube limitations |
| C. | attenuation of surface wave |
| D. | earth's curvature |
| Answer» E. | |
| 8558. |
Assertion (A): The colour signal consists of only luminance signalReason (R): In India PAL colour signal system is used. |
| 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. | |
| 8559. |
An S/N ratio of 3 expressed in db is |
| A. | 4.8 dB |
| B. | 2.4 dB |
| C. | 0.48 dB |
| D. | 0.24 dB |
| Answer» B. 2.4 dB | |
| 8560. |
To separate channels in FDM receiver we have to use |
| A. | integration |
| B. | AND gate |
| C. | band pass filter |
| D. | differentiation |
| Answer» D. differentiation | |
| 8561. |
A device with input x(t) and y(t) is characterized by y(t) = x2(t). An FM signal with frequency deviation of 90 kHz and modulating signal bandwidth of 5 kHz is applied to this device. The bandwidth of the output signal is |
| A. | 370 kHz |
| B. | 190 kHz |
| C. | 380 kHz |
| D. | 95 kHz |
| Answer» D. 95 kHz | |
| 8562. |
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 | |
| 8563. |
Assertion (A): For satellites and space probes, PRF of a radar is pretty low.Reason (R): PRF of a radar depends on the range of a radar. |
| 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 | |
| 8564. |
The material used for the magnet of moving coil cone type loudspeaker is |
| A. | steel alloy |
| B. | soft iron |
| C. | hard steel |
| D. | Alnico |
| Answer» E. | |
| 8565. |
CCIR system B employs |
| A. | 625 lines |
| B. | 625 lines with 2 : 1 interlace |
| C. | 625 lines with 4 : 1 interlace |
| D. | 500 lines with 2 : 1 interlace |
| Answer» C. 625 lines with 4 : 1 interlace | |
| 8566. |
The power to the base unit of a cordless telephone is supplied by |
| A. | battery |
| B. | AC mains |
| C. | both battery and AC mains |
| D. | either battery or AC mains |
| Answer» C. both battery and AC mains | |
| 8567. |
If velocity of sound waves in air at 0 C is 330 m/s, the velocity at 40 C is about |
| A. | 330 m/s |
| B. | 334 m/s |
| C. | 353 m/s |
| D. | 380 m/s |
| Answer» D. 380 m/s | |
| 8568. |
In FM, as bandwidth increases |
| A. | distortion increases |
| B. | distortion decreases |
| C. | distortion remains unaffected |
| D. | all |
| Answer» C. distortion remains unaffected | |
| 8569. |
A 400 W carrier is amplitude modulated with m = 0.75. If single side band suppressed carrier is used the total power in modulated wave is |
| A. | 400 W |
| B. | 512 W |
| C. | 112 W |
| D. | 56 W |
| Answer» E. | |
| 8570. |
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 | |
| 8571. |
Circuit switching, Message switching and Packet Switching Network belong to which of the following systems? |
| A. | Computer communication system |
| B. | Electromechanical communication system |
| C. | PBX system |
| D. | EPBX system |
| Answer» B. Electromechanical communication system | |
| 8572. |
The Shannon-Hartley law |
| A. | refers to noise |
| B. | defines bandwidth |
| C. | describes signalling rate |
| D. | refers to distortion |
| Answer» B. defines bandwidth | |
| 8573. |
In radar PRF depends on maximum range. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8574. |
A frequency doubler has an FM signal input at 13 MHz with a deviation of 5 kHz. The output frequency of the carrier will be |
| A. | 26 kHz |
| B. | 260 kHz |
| C. | 26 MHz |
| D. | 260 MHz |
| Answer» E. | |
| 8575. |
The characteristics of H and V sync pulses in a colour TV receiver are H sync, pulses are narrow and have frequency of 15625 HzV sync, pulses are much wider and have frequency of 50 HzH and V pulses have almost the same size but frequencies of 15625 and 50 Hz respectivelyV sync, pulses are very narrow but H sync, pulses are wide and their frequencies are 15625 Hz and 50 Hz respectively Which of the above are correct? |
| A. | 1 and 2 only |
| B. | 1 only |
| C. | 3 only |
| D. | 4 only |
| Answer» B. 1 only | |
| 8576. |
Maximum undistorted power output of a transmitter is obtained when its modulation is __________ percent. |
| A. | more than 100 |
| B. | 100 |
| C. | less than 100 |
| D. | 50 |
| Answer» C. less than 100 | |
| 8577. |
Which one of the following is not a negative resistance device? |
| A. | Gunn diode |
| B. | Tunnel diode |
| C. | Impatt diode |
| D. | Varactor diode |
| Answer» E. | |
| 8578. |
Power gain of a multicavity klystron amplifier is |
| A. | more than 30 dB |
| B. | causes retardation of all electrons |
| C. | causes acceleration of some electrons and retardation of others |
| D. | none of the above |
| Answer» B. causes retardation of all electrons | |
| 8579. |
Read the following statements about TWT It uses thermionic emission.It uses an attenuater.It is inherently a resonant device.It has broad bandwidth. Which of the above are correct? |
| A. | 1, 2, 3 and 4 |
| B. | 1, 2 and 3 |
| C. | 1, 3 and 4 |
| D. | 1, 2 and 4 |
| Answer» E. | |
| 8580. |
If a line having Z0 = 300 0 W is short circuited at far end, VSWR is |
| A. | 0 |
| B. | 1 |
| C. | |
| D. | 2 |
| Answer» D. 2 | |
| 8581. |
Consider the following statements Dissipative attenuator has a fixed value of attenuation.Reflective attenuator has a fixed value of attenuation.Both dissipative and reflective attenuators are available only with fixed attenuation.Both dissipative and reflective attenuators are available with either fixed or variable attenuation. Which of the above are correct? |
| A. | 1 only |
| B. | 1 and 2 |
| C. | 1, 2 and 3 |
| D. | 4 only |
| Answer» E. | |
| 8582. |
A klystron amplifier generally uses Pierce gun |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8583. |
For matching over a range of frequencies in a transmission line it is best to use |
| A. | a balun |
| B. | a broad band directional coupler |
| C. | double stub |
| D. | a single stub of adjustable position |
| Answer» D. a single stub of adjustable position | |
| 8584. |
Assertion (A): In the interaction region of magnetron an electron is subjected to three forces: force due to electric field, force due to magnetic field and centrifugal force.Reason (R): The mechanism of generation of microwaves, in a magnetron, involves interaction of electromagnetic fields with electrons moving in static electric and magnetic fields oriented at right angles to each other. |
| 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 | |
| 8585. |
Which of the following is wrong for a magic used to tee? |
| A. | E and H arms are decoupled |
| B. | coplanar arms are coupled |
| C. | all ports are perfectly matched |
| D. | A signal into coplanar arm splits equally between E and H arms |
| Answer» C. all ports are perfectly matched | |
| 8586. |
Ga As exhibits negative differential mobility |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8587. |
Consider the following statements Bunching of electrons occurs in two cavity klystron amplifier.Bunching of electrons occurs in multi cavity klystron amplifier.Bunching of electrons occurs in reflex cavity klystron amplifier. Which of the above statements are correct? |
| A. | 1, 2, and only |
| B. | 1, 2 and 3 only |
| C. | 1 and 3 only |
| D. | 2 and 3 only |
| Answer» C. 1 and 3 only | |
| 8588. |
Consider the following applications SwitchAttenuatorPhase shifterOscillator In which of the above can a PIN diode be used? |
| A. | 1 2 3 and 4 |
| B. | 1 2 and 3 only |
| C. | 1 and 2 only |
| D. | 2, 3 and 4 only |
| Answer» C. 1 and 2 only | |
| 8589. |
Assertion (A): For high frequency lines inductive reactance is very high as compared to ac resistance.Reason (R): Due to skin effect ac resistance of line is higher than dc resistance. |
| 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 | |
| 8590. |
If a short line is terminated in characteristic impedance it behaves as an infinite line. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8591. |
A reflex klystron oscillator uses |
| A. | one cavity resonator |
| B. | two cavity resonators |
| C. | three cavity resonators |
| D. | none of the above |
| Answer» B. two cavity resonators | |
| 8592. |
The semiconductor diode which can be used in switching circuit in microwave range is |
| A. | PIN diode |
| B. | Varactor diode |
| C. | Tunnel diode |
| D. | Gunn diode |
| Answer» B. Varactor diode | |
| 8593. |
In the given figure the reflected current wave after first reflection is |
| A. | 0.18 A |
| B. | -0.18 A |
| C. | 0.3 A |
| D. | -0.3 A |
| Answer» C. 0.3 A | |
| 8594. |
A line has an attenuation of 0.054 Np/m. The attenuation in decibels is |
| A. | 4.7 dB/m |
| B. | 0.47 dB/m |
| C. | 0.54 dB/m |
| D. | 5.4 dB/m |
| Answer» C. 0.54 dB/m | |
| 8595. |
If a line is open circuited Zin = Z0 tanh (gl). |
| A. | True |
| B. | False |
| Answer» C. | |
| 8596. |
Atomic and molecular resonance is observed in many substances |
| A. | at microwave frequencies |
| B. | at low frequencies |
| C. | at frequencies used in AM broadcast |
| D. | at both (b) and (c) |
| Answer» B. at low frequencies | |
| 8597. |
The component in the given figure is |
| A. | attenuator |
| B. | T type low pass filter |
| C. | T type high pass filter |
| D. | phase shifter |
| Answer» C. T type high pass filter | |
| 8598. |
Which one of the following is also called 'rat race'? |
| A. | E plane tee |
| B. | H plane tee |
| C. | Magic tee |
| D. | Hybrid ring |
| Answer» E. | |
| 8599. |
Radar principle is used in |
| A. | detection of aircraft |
| B. | burglar alarms |
| C. | garage door openers |
| D. | all of the above |
| Answer» E. | |
| 8600. |
In an optional fiber the refractive index of cladding material should be |
| A. | nearly 1 |
| B. | very low |
| C. | less than that of core |
| D. | more than that of core |
| Answer» D. more than that of core | |