MCQOPTIONS
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MCQOPTIONS
This section includes 50 Mcqs, each offering curated multiple-choice questions to sharpen your BEL knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
The wave length of 1 Giga hertz frequency signal is |
| A. | 10cm |
| B. | 30cm |
| C. | 3cm |
| D. | 1cm |
| Answer» C. 3cm | |
| 2. |
If a parallel LC circuit is excited at frequency less than its resonant frequency, the nature of its effective impedance is |
| A. | Resistive |
| B. | Inductive |
| C. | Capacitive |
| D. | None of these of these |
| Answer» C. Capacitive | |
| 3. |
Two coils (inductors) connected in series have a combined inductance of 15mH. When terminals of one of the coils are reversed and connected to the other, the combined inductance is measured to be 9mH. What is the value of mutual inductance |
| A. | 1.5mH |
| B. | 3mH |
| C. | 6mH |
| D. | 12mH |
| Answer» B. 3mH | |
| 4. |
ICs made by sputtering of materials on a ceramic substrate are called |
| A. | Monolithic |
| B. | Hybrid |
| C. | Thick film |
| D. | Thin film |
| Answer» E. | |
| 5. |
In a monolithic IC, resistors are formed from |
| A. | Ceramic materials |
| B. | Copper |
| C. | P-type semiconductor |
| D. | Aluminium deposition |
| Answer» D. Aluminium deposition | |
| 6. |
If several stations in a network want to use a single channel without interfering with one another, the technique used is called |
| A. | Carrier sense |
| B. | Phantom-freeze |
| C. | Packet switching |
| D. | Multiplexing |
| Answer» E. | |
| 7. |
Ethernet is a name of |
| A. | Medium of computer communication |
| B. | Network for computer communication |
| C. | Procedures for computer communication network |
| D. | Software for computer communication |
| Answer» C. Procedures for computer communication network | |
| 8. |
A gateway |
| A. | Is a place where radars are connected |
| B. | Permits dissimilar networks to communicate |
| C. | Bifurcates the RF path of a transmitter |
| D. | Is a feeder cable |
| Answer» C. Bifurcates the RF path of a transmitter | |
| 9. |
HDLC is a term for |
| A. | Data communication protocol |
| B. | Synchronizing pulses |
| C. | Gain control in receivers |
| D. | Error checking |
| Answer» B. Synchronizing pulses | |
| 10. |
Monopulse technique is used in |
| A. | Radar |
| B. | Radio relay |
| C. | Data communication |
| D. | Fibre-optics |
| Answer» B. Radio relay | |
| 11. |
Mono-mode is a term used in |
| A. | Fibre-optics |
| B. | Radar |
| C. | Satellite communication |
| D. | Magnetics |
| Answer» B. Radar | |
| 12. |
The most effective anti-jamming technique is |
| A. | Frequency hopping |
| B. | Spread Spectrum |
| C. | Frequency synthesis |
| D. | Burst transmission |
| Answer» B. Spread Spectrum | |
| 13. |
A modem is a device used for |
| A. | Digitizing voice data |
| B. | Transmission of data on lines |
| C. | Modulating and demodulating signals sent on a line |
| D. | Suppressing noise interference |
| Answer» D. Suppressing noise interference | |
| 14. |
A typical fibre-optic detector is |
| A. | Step recovery diode |
| B. | Light emitting diode |
| C. | Avalanche photo diode |
| D. | Field effect transistor |
| Answer» D. Field effect transistor | |
| 15. |
For the national TV and ratio network, INSAT-IB uses |
| A. | 400MHz |
| B. | 2.5GHz |
| C. | 2.5 and 5GHz |
| D. | 4 and 6 GHz |
| Answer» E. | |
| 16. |
The silicon solar cell is a |
| A. | Photo conductive |
| B. | Photo emissive |
| C. | Photo voltaic |
| D. | Photo resistive |
| Answer» D. Photo resistive | |
| 17. |
The signal propagation time in milliseconds for a geosynchronous satellite is |
| A. | 540 |
| B. | 270 |
| C. | 135 |
| D. | 100 |
| Answer» D. 100 | |
| 18. |
A rectangular waveguide behaves like a filter of |
| A. | Band pass |
| B. | High pass |
| C. | Low pass |
| D. | Band stop |
| Answer» C. Low pass | |
| 19. |
Strapping is used in a magnetron to |
| A. | Prevent mode jumping |
| B. | Reduce frequency drift |
| C. | Ensure proper bunching |
| D. | Dissipate heat |
| Answer» B. Reduce frequency drift | |
| 20. |
A duplexer is used to |
| A. | Receive two signals in one antenna |
| B. | Prevent interference between two antenna |
| C. | Mix two signals to the same antenna |
| D. | Allow one antenna for both transmission and reception |
| Answer» E. | |
| 21. |
Frequency in the UHF range is propagate by waves of |
| A. | Ground |
| B. | sky |
| C. | Space |
| D. | Surface |
| Answer» D. Surface | |
| 22. |
To overcome fading in a ship-to-ship communication system we can efficiently use |
| A. | Broadband Antenna |
| B. | Directional Antenna |
| C. | Space Diversity |
| D. | Frequency Diversity |
| Answer» E. | |
| 23. |
Microwave repeaters are typically |
| A. | 25 |
| B. | 50 |
| C. | 75 |
| D. | 100 Kms apart |
| Answer» C. 75 | |
| 24. |
A transmission line of VSWR 2 has a reflection coefficient |
| A. | 0.25 |
| B. | 0.5 |
| C. | 75 |
| D. | 0 |
| Answer» D. 0 | |
| 25. |
A PIN diode is microwave |
| A. | Oscillator |
| B. | Mixer |
| C. | Detector |
| D. | Switch |
| Answer» E. | |
| 26. |
The impedance of a 3 element yagi antenna is around |
| A. | 75W |
| B. | 300W |
| C. | 50W |
| D. | 100W |
| Answer» C. 50W | |
| 27. |
VHF signals are propagated |
| A. | Via the ionosphere |
| B. | Along the ground |
| C. | Through the troposphere |
| D. | By reflection in ionosphere |
| Answer» C. Through the troposphere | |
| 28. |
The frame rate per second used in India TV is |
| A. | 60 |
| B. | 50 |
| C. | 25 |
| D. | 30 |
| Answer» D. 30 | |
| 29. |
A wein bridge is used for measurement of |
| A. | Resistance |
| B. | Capacitance |
| C. | Inductance |
| D. | Audio frequency |
| Answer» E. | |
| 30. |
The cathode ray oscilloscope can be used to measure |
| A. | Frequency |
| B. | Time interval |
| C. | Voltage |
| D. | All the above |
| Answer» E. | |
| 31. |
The term critical frequency in Ionospheric propagation is |
| A. | Lowest frequency reflected by Ionosphere |
| B. | Highest frequency reflected by the Ionosphere at vertical incidence |
| C. | Lowest frequency reflected by the Ionosphere at vertical incidence |
| D. | Lowest communication frequency possible |
| Answer» C. Lowest frequency reflected by the Ionosphere at vertical incidence | |
| 32. |
Top loading is used in antennas for |
| A. | Decrease in impedance |
| B. | Increase in bandwidth |
| C. | Increase in effective height |
| D. | Decease the height |
| Answer» D. Decease the height | |
| 33. |
A half wave folded dipole has a radiation resistance of |
| A. | 72 W |
| B. | 50W |
| C. | 144W |
| D. | 288W |
| Answer» E. | |
| 34. |
Stub matching eliminates standing wave on |
| A. | Load side of the stub |
| B. | Source side of the stub |
| C. | Both sides |
| D. | On the stub |
| Answer» D. On the stub | |
| 35. |
A 32 channel 8 bit PCM system samples at 8 KHz rate. The overall bit rate in kilobits per second will be |
| A. | 2048 |
| B. | 2000 |
| C. | 1920 |
| D. | 64 |
| Answer» B. 2000 | |
| 36. |
Noise generated by a resistor is dependent on |
| A. | Its Value |
| B. | Its temperature |
| C. | Both value and temp |
| D. | None of these |
| Answer» D. None of these | |
| 37. |
A 100 MHz FM carrier, modulated by a 5 KHz sine wave deviates by 50 KHz If the frequency of the modulating sine wave is doubled, the deviation will |
| A. | Double |
| B. | Half |
| C. | Quadruple |
| D. | Have no change |
| Answer» E. | |
| 38. |
A plate modulated class C RF amplifier produces 100 KW of radiated power at 100 % modulation. The modulating audio amplifier supplies approximately |
| A. | 25KW |
| B. | 33KW |
| C. | 50KW |
| D. | 66KW |
| Answer» C. 50KW | |
| 39. |
A device which behaves like SCRs is |
| A. | UJT |
| B. | Triac |
| C. | MOSFET |
| D. | SRD |
| Answer» C. MOSFET | |
| 40. |
MOSFET operates in |
| A. | Depletion mode only |
| B. | Enhancement mode only |
| C. | Depletion and enhancement mode |
| D. | None of these of the above |
| Answer» D. None of these of the above | |
| 41. |
The rise time of an amplifier is 200 nsec. Its bandwidth is |
| A. | 70MHz |
| B. | 140MHz |
| C. | 100MHz |
| D. | 1.75Mhz |
| Answer» E. | |
| 42. |
The noise figure of an ideal amplifier in decibel is |
| A. | 0.5 |
| B. | 0 |
| C. | 1 |
| D. | 10 |
| Answer» C. 1 | |
| 43. |
A silicon transistor has a leakage current 1cbo = 1 ma. If the temp. rises by 50o C the leakage current will be |
| A. | 30 ma |
| B. | 32ma |
| C. | 50ma |
| D. | no change |
| Answer» C. 50ma | |
| 44. |
The temperature coefficient of an intrinsic semiconductor is |
| A. | Positive |
| B. | Negative |
| C. | Zero |
| D. | Like metals |
| Answer» C. Zero | |
| 45. |
Barrier voltage in a P-N junction is caused by |
| A. | Thermally generated electrons and holes |
| B. | Diffusion of majority carriers across the junction |
| C. | Migration of minority carriers across the junction |
| D. | Flow of drift current |
| Answer» C. Migration of minority carriers across the junction | |
| 46. |
An example of volatile memory is |
| A. | RAM |
| B. | ROM |
| C. | EPROM |
| D. | Magnetic tape |
| Answer» B. ROM | |
| 47. |
An index register in a computer is for |
| A. | Arithmetic and logic functions |
| B. | Storage of results |
| C. | Modifying the address |
| D. | Counting the no of programmes |
| Answer» D. Counting the no of programmes | |
| 48. |
A binary half adder |
| A. | Adds two binary digits and produces their sum and carry |
| B. | Adds half the sum to the carry |
| C. | Adds two binary digits and carry from previous addition |
| D. | Adds two binary digits at half the speed |
| Answer» B. Adds half the sum to the carry | |
| 49. |
A Multiplexer has |
| A. | Multiple inputs and single output |
| B. | Single input and Multiple outputs |
| C. | Multiple inputs and Multiple outputs |
| D. | Multiple inputs for Storage of Data |
| Answer» B. Single input and Multiple outputs | |
| 50. |
The gray code equivalent of binary 1100 is |
| A. | 1011 |
| B. | 1101 |
| C. | 1010 |
| D. | 1100 |
| Answer» D. 1100 | |