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. |
The attenuation in waveguide above to cut off frequency |
| A. | very high |
| B. | very low |
| C. | zero |
| D. | infinite |
| Answer» C. zero | |
| 2. |
Tropospheric scatter propagation is not subject to any fading. |
| A. | True |
| B. | False |
| Answer» C. | |
| 3. |
When a current carrying conductor is brought into magnetic field, the force that moves the conductor depends upon |
| A. | the value of current |
| B. | the weight of the conductor |
| C. | the direction of the conductor |
| D. | none of the above |
| Answer» B. the weight of the conductor | |
| 4. |
Which of the following is multiband HF receiving antenna? |
| A. | Square loop |
| B. | Log-periodic |
| C. | Conical horn |
| D. | Folded dipole |
| Answer» C. Conical horn | |
| 5. |
A rectangular waveguide is a |
| A. | rectangular conducting wire to propagate electromagnetic waves |
| B. | hollow rectangular walled room carrying electromagnetic wave |
| C. | hollow rectangular conducting tube through which electromagnetic waves can be propagated |
| D. | tube antenna to transmit and receive electromagnetic waves |
| Answer» D. tube antenna to transmit and receive electromagnetic waves | |
| 6. |
The frequency range for satellite communication is |
| A. | 3 to 30 kHz |
| B. | 300 to 3000 kHz |
| C. | 3000 to 30000 MHz |
| D. | 30000 to 300000 MHz |
| Answer» D. 30000 to 300000 MHz | |
| 7. |
Which of the following is not a wideband antenna? |
| A. | Marconi |
| B. | Discone |
| C. | Helical |
| D. | Folded dipole |
| Answer» B. Discone | |
| 8. |
The term critical frequency denotes |
| A. | the lowest frequency that is reflected by the ionosphere |
| B. | the highest frequency that is reflected by the ionosphere at vertical distance |
| C. | the lowest frequency by which communication is possible between two given points |
| D. | none of the above |
| Answer» C. the lowest frequency by which communication is possible between two given points | |
| 9. |
The important postulate arising out of Maxwell's modification of Ampere's law is |
| A. | a changing magnetic field produces an electric field |
| B. | a changing electric field produces a magnetic field |
| C. | a motional e.m.f. is produced by a coil moving in a magnetic field |
| D. | a steady current produce a magnetic field |
| Answer» C. a motional e.m.f. is produced by a coil moving in a magnetic field | |
| 10. |
The polarization phenomena in Faraday rotation |
| A. | is non-reciprocal |
| B. | exists along perpendicular direction |
| C. | exists along the axis of array |
| D. | does not exist |
| Answer» B. exists along perpendicular direction | |
| 11. |
Which of the following relations is valid for a spherical surface? |
| A. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/193-168-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/193-168-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/193-168-3.png"> |
| D. | None of the above |
| Answer» D. None of the above | |
| 12. |
Which antenna is frequently used for local area transmission at UHF/VHF? |
| A. | Ground monopole |
| B. | Turnstile antenna |
| C. | Slot antenna |
| D. | Loop antenna |
| Answer» B. Turnstile antenna | |
| 13. |
When there is rapid attenuation of field inside the conductor, the field current are concentrated close to the surface of the conductor; this phenomenon is called |
| A. | skin effect |
| B. | EM concentration effect |
| C. | Faraday's effect |
| D. | Ohm's effect |
| Answer» B. EM concentration effect | |
| 14. |
The induction field of short current element varies as |
| A. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/201-340-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/201-340-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/201-340-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/201-340-4.png"> |
| Answer» E. | |
| 15. |
In binomial arrays the elimination of secondary lobes takes place |
| A. | at the cost of directivity |
| B. | at the cost of gain |
| C. | both (a) and (b) |
| D. | none of the above |
| Answer» D. none of the above | |
| 16. |
The characteristic equation of plane wave in E independent of two dimensions y and z is |
| A. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/191-122-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/191-122-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/191-122-3.png"> |
| D. | none of the above |
| Answer» B. <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/191-122-2.png"> | |
| 17. |
Q-factor of a transmission line at resonance is |
| A. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/188-41-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/188-41-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/188-41-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/188-41-4.png"> |
| Answer» B. <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/188-41-2.png"> | |
| 18. |
Troposphere is the upper part of the Earth's atmosphere which absorbs large quantities of Sun's radiations. |
| A. | True |
| B. | False |
| Answer» C. | |
| 19. |
For resonant long wire antenna 'n' half wavelength long in free space, if 'n' is increased then inclination of the major lobe with wire axis will __________ . |
| A. | increases |
| B. | decreases |
| C. | remains same |
| D. | none |
| Answer» C. remains same | |
| 20. |
Radar antennas are usually |
| A. | dipoles |
| B. | yagi antennas |
| C. | parabolic dishes |
| D. | none of the above |
| Answer» D. none of the above | |
| 21. |
The radio horizon for space waves is about three-fourth as for as the optical horizon. |
| A. | True |
| B. | False |
| Answer» C. | |
| 22. |
A waveguide behave as |
| A. | high Pass filter |
| B. | low Pass filter |
| C. | band Pass filter |
| D. | all Pass filter |
| Answer» B. low Pass filter | |
| 23. |
Triatics are |
| A. | small height antenna directly mounted on jeeps, ships, etc. |
| B. | the towers or masts which are used as radiators |
| C. | the towers or masts which are not used as radiators |
| D. | supports for antenna conductors. |
| Answer» D. supports for antenna conductors. | |
| 24. |
The total field produced by an antenna array system at a distance from it is |
| A. | sum of the field produced by the individual antennas of the array system |
| B. | directional gain of antenna |
| C. | linear antenna gain |
| D. | vector sum of the field produced by the individual antennas of the array system |
| Answer» E. | |
| 25. |
A perfect conductor is a perfect absorber of electromagnetic waves. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 26. |
In a lead acid cell the density of the acid gives an indication of |
| A. | the level of the acid |
| B. | the eventual damages caused to the plates |
| C. | the charge of the battery |
| D. | the e.m.f. of the battery |
| Answer» D. the e.m.f. of the battery | |
| 27. |
A (0.75 - j50) ohm load is connected to a coaxial transmission line of Z0 = 75 ohms at a frequency of 10 GHz Which of the following will be the best method of matching? |
| A. | Connecting an inductance at the end |
| B. | Connecting a short circuited stub at the load |
| C. | Connecting a capacitance at some distance from the load |
| D. | Connecting a short circuited stub at some specified distance from the load |
| Answer» E. | |
| 28. |
Television receiver antenna is usually |
| A. | loop type |
| B. | yagi antenna |
| C. | parabolic dishes |
| D. | none of the above |
| Answer» C. parabolic dishes | |
| 29. |
In figure the current distribution is represented by |
| A. | curve A |
| B. | curve B |
| C. | curve C |
| D. | curve D |
| Answer» D. curve D | |
| 30. |
Half power point directions for broadside is |
| A. | 60 |
| B. | 30 |
| C. | 45 |
| D. | at any angle |
| Answer» B. 30 | |
| 31. |
What will happen to a bird sitting on a conductor? |
| A. | It will die of shock |
| B. | It will not die of shock because its claws are insulated |
| C. | It will not die because it is insulated from earth and other conductors |
| D. | None of the above |
| Answer» D. None of the above | |
| 32. |
For a distortionless line, the parameters are related as |
| A. | R/G = L/C |
| B. | R/L = 1 |
| C. | R/G = C/L |
| D. | RG = LC |
| Answer» B. R/L = 1 | |
| 33. |
A field can be |
| A. | harmonic |
| B. | divergence less |
| C. | solenoidal |
| D. | rotational |
| Answer» E. | |
| 34. |
Phase velocity of waves propagating in a hollow metal waveguide is |
| A. | greater than the group velocity |
| B. | less than the velocity of light in free space |
| C. | equal to the velocity of light in free space |
| D. | equal to group velocity |
| Answer» B. less than the velocity of light in free space | |
| 35. |
Good smoothing factor of a coil depends on |
| A. | inductance of the coil |
| B. | terminal voltage |
| C. | cross-sectional area of the wire of the coil |
| D. | property of the wire of the coil |
| Answer» E. | |
| 36. |
VLF is generally used for |
| A. | telegraphy |
| B. | satellite communication |
| C. | instrument landing system |
| D. | all of the above |
| Answer» B. satellite communication | |
| 37. |
In electromagnetic wave polarization is caused by |
| A. | refraction |
| B. | reflection |
| C. | longitudinal nature of electromagnetic waves |
| D. | transverse nature of electromagnetic waves |
| Answer» E. | |
| 38. |
Television signals are propagated as ground waves. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 39. |
In a rectangular waveguide if operating frequency is greater than cut off frequency then propagation constant is |
| A. | purely real |
| B. | purely imaginary |
| C. | equal to unit |
| D. | a complex number |
| Answer» C. equal to unit | |
| 40. |
Isotropic radiator is one that radiates energy |
| A. | uniformly in all direction |
| B. | inside a hollow sphere |
| C. | in a well defined isotropic direction |
| D. | none of the above |
| Answer» B. inside a hollow sphere | |
| 41. |
The characteristic impedance of loss less transmission line is |
| A. | L/R |
| B. | <span class="root">L/C</span> |
| C. | <span class="root">1/LC</span> |
| D. | <span class="root">C/L</span> |
| Answer» C. <span class="root">1/LC</span> | |
| 42. |
Industrial heating furnaces such as arc and induction furnaces operate on __________ power factor |
| A. | low leading |
| B. | low lagging |
| C. | high leading |
| D. | very low lagging |
| Answer» E. | |
| 43. |
F2 layer of atmosphere extends from |
| A. | 250 km to 400 km |
| B. | 150 km to 250 km |
| C. | 50 km to 150 km |
| D. | 15 km to 50 km |
| Answer» B. 150 km to 250 km | |
| 44. |
Whereas resonant antenna is bidirectional, non-resonant antenna is unidirectional. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 45. |
In radar system if the antenna diameter is increased by a factor of 4, the minimum range will increased by a factor of |
| A. | <span class="root">1</span> |
| B. | 2 |
| C. | 2 |
| D. | <span class="root">2</span> |
| E. | 4 |
| Answer» E. 4 | |
| 46. |
Which of the following antennas is /4 length? |
| A. | Dipole |
| B. | Marconi |
| C. | Monopole |
| D. | Parabolic |
| Answer» B. Marconi | |
| 47. |
The pure capacitor connected across an A.C. voltage consumed 20 W. This is due to |
| A. | the capacitive reactance in ohms |
| B. | the current flowing in the capacitor |
| C. | the fused capacitor was a big one |
| D. | none of the above |
| Answer» E. | |
| 48. |
A dominant wave is characterised by which of the following? |
| A. | No attenuation |
| B. | Lowest cut off wavelength |
| C. | Highest cut off wavelength |
| D. | All of the above |
| Answer» D. All of the above | |
| 49. |
In order to receive a vertical polarized wave, the conductor of the dipole should be mounted |
| A. | horizontally |
| B. | vertically |
| C. | at an angle of 45 |
| D. | at an angle of 90 |
| Answer» C. at an angle of 45 | |
| 50. |
Capacitance hats are installed on low frequency antenna is |
| A. | increase the electrical length |
| B. | reduce the electrical length |
| C. | protect against lightening |
| D. | protect against corona effects |
| Answer» B. reduce the electrical length | |