MCQOPTIONS
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MCQOPTIONS
This section includes 657 Mcqs, each offering curated multiple-choice questions to sharpen your Testing Subject knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
If output power of a radio receiver is doubled, its volume is increased by __________ dB. |
| A. | 2 |
| B. | 3 |
| C. | 1 |
| D. | -3 |
| Answer» C. 1 | |
| 2. |
To eliminate ghosts in the picture |
| A. | use a longer transmission line |
| B. | connect a booster |
| C. | change the antenna orientation of location |
| D. | twist the transmission line |
| Answer» D. twist the transmission line | |
| 3. |
The frequency range of 300 kHz to 3000 kHz is known as |
| A. | low frequency |
| B. | medium frequency |
| C. | high frequency |
| D. | very high frequency |
| Answer» C. high frequency | |
| 4. |
Assertion (A): In FM the frequency of the carrier is varied by the modulating voltageReason (R): FM and PM are two forms of angle modulation. |
| 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 | |
| 5. |
For telegraphy the most commonly used modulation system is |
| A. | FSK |
| B. | two tone modulation |
| C. | PCM |
| D. | single tone modulation |
| Answer» B. two tone modulation | |
| 6. |
For a low level AM system, the amplifiers modulated stage must be |
| A. | linear devices |
| B. | harmonic devices |
| C. | class C amplifiers |
| D. | non-linear devices |
| Answer» B. harmonic devices | |
| 7. |
Which of the following does not cause losses in optical fibre cables? |
| A. | Stepped index operation |
| B. | Impurities |
| C. | Microbending |
| D. | Attenuation in glass |
| Answer» B. Impurities | |
| 8. |
Commercial Frequency deviation of FM is |
| A. | 70 kHz |
| B. | 75 kHz |
| C. | 80 kHz |
| D. | 65 kHz |
| Answer» C. 80 kHz | |
| 9. |
The colour of an object is decided by |
| A. | the reflected colour |
| B. | the wavelength transmitted through it |
| C. | reflected colour for opaque object and wavelength transmitted through it for transparent objects |
| D. | none of the above |
| Answer» D. none of the above | |
| 10. |
In Pulse Code Modulation system |
| A. | large bandwidth is required |
| B. | quantising noise can be overcome by companding |
| C. | quantising noise can be reduced by decreasing the number of standard levels |
| D. | suffers from the disadvantage of its incompatibly with TDM |
| Answer» B. quantising noise can be overcome by companding | |
| 11. |
Waveform shown in figure is that for |
| A. | FM |
| B. | PCM |
| C. | AM-DSB |
| D. | AM-SSB |
| Answer» D. AM-SSB | |
| 12. |
The disadvantage of FM over AM is that |
| A. | high output power is needed |
| B. | high modulating power is needed |
| C. | noise is very high for high frequency |
| D. | large bandwidth is required |
| Answer» E. | |
| 13. |
Which of the following is a digital modulation technique? |
| A. | PCM |
| B. | PSK |
| C. | DM |
| D. | All |
| Answer» E. | |
| 14. |
If in a broadcasting studio, a 1000 kHz carrier is modulated by an audio signal of frequency range 100-5000 kHz, the width of channel is __________ kHz. |
| A. | 5 |
| B. | 4.9 |
| C. | 995 |
| D. | 10 |
| Answer» E. | |
| 15. |
Which one of the following is analog? |
| A. | PCM |
| B. | PWM |
| C. | Delta modulation |
| D. | Differential PCM |
| Answer» C. Delta modulation | |
| 16. |
Which of the following is used to generate PDM? |
| A. | Free running multi-vibrator |
| B. | Monostable multi-vibrator |
| C. | JK flip-flop |
| D. | Schmitt trigger |
| Answer» C. JK flip-flop | |
| 17. |
A zero mean white Gaussian noise is passed through an ideal low pass filter of bandwidth 10 kHz. The output of the samples so obtained would be |
| A. | correlated |
| B. | statistically independent |
| C. | uncorrelated |
| D. | orthogonal |
| Answer» C. uncorrelated | |
| 18. |
What is the purpose of peak clipper circuits in radio transmitters? |
| A. | To prevent overmodulation |
| B. | To reduce bandwidth |
| C. | To increase bandwidth |
| D. | To regulate oscillator I/P voltage |
| Answer» B. To reduce bandwidth | |
| 19. |
In case of frequency modulation, modulating voltage remains constant if the modulating frequency is lowered, then |
| A. | amplitude of distant sidebands decreases |
| B. | amplitude of distant sidebands increases |
| C. | amplitude of distant sidebands remains constant |
| D. | amplitude of distant sidebands first increases, then decreases |
| Answer» C. amplitude of distant sidebands remains constant | |
| 20. |
If sampling is done at the rate of 10 kHz. The bandwidth required is |
| A. | 35 kHz |
| B. | 70 kHz |
| C. | 10 kHz |
| D. | 1280 kHz |
| Answer» B. 70 kHz | |
| 21. |
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 | |
| 22. |
Full duplex operation-permits transmission in both directions at the same time. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 23. |
In a TV receiver antenna the length of reflector rod |
| A. | is the same as that of dipole |
| B. | is less than that of dipole |
| C. | is more than that of dipole |
| D. | may be equal, more or less than that of dipole |
| Answer» D. may be equal, more or less than that of dipole | |
| 24. |
The modulation index of an FM is changed from 0 to 1. How does the transmitted power change? |
| A. | Gets halved |
| B. | Gets doubled |
| C. | Gets increased by 50 percent |
| D. | Remains unchanged |
| Answer» D. Remains unchanged | |
| 25. |
For AM receivers the standard IF frequency is |
| A. | 106 kHz |
| B. | 455 kHz |
| C. | 1.07 MHz |
| D. | 10.7 MHz |
| Answer» C. 1.07 MHz | |
| 26. |
The rate at which information can be carried through a communication channel depends on |
| A. | carrier frequency |
| B. | bandwidth |
| C. | transmission loss |
| D. | transmitted power |
| Answer» C. transmission loss | |
| 27. |
Some types of traps used in video IF amplifier of colour TV are |
| A. | shunt traps |
| B. | series traps |
| C. | absorption traps |
| D. | all of the above |
| Answer» E. | |
| 28. |
Direct and reflected sound waves may interfere with each other. |
| A. | True |
| B. | False |
| Answer» C. | |
| 29. |
A carrier is simultaneously modulated by two sine waves having modulation indices of 0.4 and 0.3. The total modulation index will be |
| A. | 0.1 |
| B. | 0.7 |
| C. | 0.5 |
| D. | 0.35 |
| Answer» D. 0.35 | |
| 30. |
Which of the following is an indirect way of generating FM? |
| A. | Armstrong modulator |
| B. | Varactor diode modulator |
| C. | Reactance FET modulator |
| D. | Reactance bipolar transistor |
| Answer» B. Varactor diode modulator | |
| 31. |
A 1000 kHz carrier is simultaneously modulated with 300 Hz, 800 Hz and 2 kHz audio sine waves. Which of the following frequency is least likely to be present in the output? |
| A. | 1002 kHz |
| B. | 1000 kHz |
| C. | 999.2 kHz |
| D. | 998.0 kHz |
| Answer» C. 999.2 kHz | |
| 32. |
In radar systems PRF stands for |
| A. | Power Return Factor |
| B. | Pulse Return Factor |
| C. | Pulse Repetition Frequency |
| D. | Pulse Response Factor |
| Answer» D. Pulse Response Factor | |
| 33. |
Circular polarization |
| A. | is useful in reducing depolarization effect on received wave |
| B. | involves critical alignment of transmitting and receiving antenna |
| C. | is useful in discrimination between reception of adjacent beams |
| D. | none of the above |
| Answer» B. involves critical alignment of transmitting and receiving antenna | |
| 34. |
An FM radio receiver which is tuned to a 91.6 MHz broadcast station may receive an image frequency of __________ MHz. |
| A. | 102.3 |
| B. | 113 |
| C. | 70.2 |
| D. | 80.9 |
| Answer» C. 70.2 | |
| 35. |
When the length of antenna is a whole wavelength |
| A. | the radiation at right angles is zero |
| B. | the radiation at right angles is maximum |
| C. | the radiation is zero in all directions |
| D. | the radiation is maximum in all directions |
| Answer» B. the radiation at right angles is maximum | |
| 36. |
A 400 W carrier is amplitude modulated with m = 0.75. The total power in AM is |
| A. | 400 W |
| B. | 512 W |
| C. | 588 W |
| D. | 650 W |
| Answer» C. 588 W | |
| 37. |
For a given carrier wave, maximum undistorted power is transmitted when value of modulation is |
| A. | 1 |
| B. | 0.8 |
| C. | 0.5 |
| D. | 0 |
| Answer» B. 0.8 | |
| 38. |
A telephone channel requires a bandwidth of about |
| A. | 1 kHz |
| B. | 3 kHz |
| C. | 10 kHz |
| D. | 50 kHz |
| Answer» C. 10 kHz | |
| 39. |
As per Shannon-Hartley theorem, a noise less Gaussian channel has |
| A. | zero capacity |
| B. | infinite capacity |
| C. | small capacity |
| D. | none of the above |
| Answer» C. small capacity | |
| 40. |
DVD uses |
| A. | Laser beam for both recording and playback |
| B. | Laser beam for recording and video head for playback |
| C. | Video head for recording and laser beam for playback |
| D. | None of the above |
| Answer» B. Laser beam for recording and video head for playback | |
| 41. |
Fourier analysis indicate that a square wave can be represented as |
| A. | a fundamental sine wave and odd harmonics |
| B. | a fundamental sine wave and even harmonics |
| C. | a fundamental sine wave and harmonics |
| D. | fundamental and subharmonic sine waves |
| Answer» B. a fundamental sine wave and even harmonics | |
| 42. |
If the target cross-section is changing, the best scanning system for accurate tracking is |
| A. | lobe switching |
| B. | monopulse |
| C. | sequential lobing |
| D. | conical scanning |
| Answer» C. sequential lobing | |
| 43. |
Audio systems use transverse recording. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 44. |
If e = 10 sin(108 t + 3 sin 104 t) then the modulation index is |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» D. 4 | |
| 45. |
Frequency modulation consists in |
| A. | varying the frequency and amplitude of the carrier in accordance with the instantaneous value of modulating signal |
| B. | varying the amplitude of the carrier in accordance with the instantaneous value of the modulating voltage |
| C. | varying the frequency of the carrier voltage in accordance with the instantaneous value of the modulating voltage |
| D. | vary the frequency of the carrier voltage |
| Answer» D. vary the frequency of the carrier voltage | |
| 46. |
How can the quantizing noise be reduced? |
| A. | By using de-emphasis circuit |
| B. | By using RF amplifier in the receiver |
| C. | By increasing the number of quantization levels |
| D. | By sending sloping pulses |
| Answer» D. By sending sloping pulses | |
| 47. |
In high power AM transmission, modulation is done at |
| A. | IF stage |
| B. | buffer stage |
| C. | RF stage |
| D. | oscillator stage |
| Answer» E. | |
| 48. |
In a CD player the laser uses |
| A. | silicon semiconductor |
| B. | silicon/germanium semiconductor |
| C. | aluminium gallium arsenide semiconductor |
| D. | none of the above |
| Answer» D. none of the above | |
| 49. |
The noise sources shot noise, partition noise and thermal noise are associated with which component |
| A. | BJT |
| B. | diode |
| C. | resistor |
| D. | capacitor |
| Answer» B. diode | |
| 50. |
Leak type bias is used in a plate-modulated class C amplifier to |
| A. | prevent tuned circuit damping |
| B. | prevent over modulation |
| C. | increase the bandwidth |
| D. | prevent excessive grid current |
| Answer» C. increase the bandwidth | |