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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.
| 1301. |
Which of the following term does not apply to the Yagi-Uda array? |
| A. | High gain |
| B. | Folded dipole |
| C. | Parasitic |
| D. | Good bandwidth |
| Answer» B. Folded dipole | |
| 1302. |
A ship-to-ship communication system is plagued by fading. The best solution seems to be the use of |
| A. | space diversity |
| B. | frequency diversity |
| C. | a broad band antenna |
| D. | a more directional antenna |
| Answer» C. a broad band antenna | |
| 1303. |
Divergence theorem relate surface integration with volume integration as |
| A. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/193-165-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/193-165-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/193-165-3.png"> |
| D. | none of the above |
| Answer» B. <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/193-165-2.png"> | |
| 1304. |
A unipole is also known as |
| A. | omnidirectional radiator |
| B. | unidirectional radiator |
| C. | line radiator |
| D. | none of the above |
| Answer» B. unidirectional radiator | |
| 1305. |
Which one of the following is not a correct Maxwell equation? |
| A. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/198-274-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/198-274-2.png"> |
| C. | x D = |
| D. | <i>f</i> |
| E. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/198-274-3.png"> |
| Answer» C. x D = | |
| 1306. |
When the height of a vertical earthed antenna is less than /4 |
| A. | the base input impedance will be capacitive |
| B. | the base input impedance will be purely resistive |
| C. | the base input impedance will be inductive |
| D. | the base input impedance will be negligibly small |
| Answer» B. the base input impedance will be purely resistive | |
| 1307. |
If a wave is propagated in free space, it will be in nature of |
| A. | TE |
| B. | TM |
| C. | TEM |
| D. | Any one of above |
| Answer» D. Any one of above | |
| 1308. |
To couple a coaxial line to a parallel wire line, it is best to use a |
| A. | balun |
| B. | slotted line |
| C. | quarter wave transformer |
| D. | directional coupler |
| Answer» B. slotted line | |
| 1309. |
Which of the following is /2 length? |
| A. | Marconi |
| B. | Hertz |
| C. | Parabolic |
| D. | Yagi-uda |
| Answer» C. Parabolic | |
| 1310. |
Which of the following is the main difference between waveguide and transmission line? |
| A. | Waveguides cannot be coupled to coaxial lines |
| B. | Waveguides have no standing wave ratio |
| C. | Transmission line does not suffer from the effect of low cut off frequency |
| D. | Waveguides are not distributed like transmission lines |
| Answer» D. Waveguides are not distributed like transmission lines | |
| 1311. |
The number of lobes on each side of a 31 resonant antenna will be |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 6 |
| Answer» E. | |
| 1312. |
Analysis of EM wave in waveguide based on |
| A. | circuit theory |
| B. | field theory |
| C. | optical theory |
| D. | both (a) and (b) |
| Answer» C. optical theory | |
| 1313. |
The main difference between the broadside arrays and end fire arrays is that |
| A. | individual elements are fed with same current in broadside arrays and of different magnitude in end fire arrays |
| B. | in broadside arrays the elements are equidistant whereas in end fire array the distance between elements increases progressively |
| C. | the total number of elements in broadside array is always one and a half times that of elements in end fire arrays |
| D. | in broadside array the individual elements are fed in, out of phase by 180 whereas in end fire array individual elements are fed with currents of equal magnitude but their phases vary progressively along the line in such a way as to make the entire arrangement substantially unidirectional |
| Answer» E. | |
| 1314. |
The charges between a hollow and solid metal spheres reside |
| A. | through out in both |
| B. | on outer surface in hollow and through out in solid |
| C. | on the outer surface in both |
| D. | none of the above |
| Answer» D. none of the above | |
| 1315. |
For an incident wave which is normal on the perfect dielectric the reflection factor is given by (where 1 and 2 are the permittivities of 1st and 2nd medium respectively) |
| A. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/191-116-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/191-116-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/191-116-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/191-116-4.png"> |
| Answer» E. | |
| 1316. |
For TE or TM modes of propagation in bounded media, the phase velocity is |
| A. | independent of frequency |
| B. | is a linear function of frequency |
| C. | is a non-linear function of frequency |
| D. | can be frequency dependent or frequency independent on the source |
| Answer» D. can be frequency dependent or frequency independent on the source | |
| 1317. |
Intrinsic or characteristic impedance of free space has a value of |
| A. | 120 ohm |
| B. | 73 ohm |
| C. | 73 ohm |
| D. | 120 ohm |
| Answer» E. | |
| 1318. |
Two LOS antennas having power gains of G1 and G2 are separated transmitted power, Pr is received power turn Pr/Pt will be proportional to |
| A. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/204-425-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/204-425-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/204-425-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/204-425-4.png"> |
| Answer» B. <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/204-425-2.png"> | |
| 1319. |
End fire array has narrow bandwidth. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 1320. |
2 is |
| A. | vector |
| B. | scalar |
| C. | depend on direction |
| D. | none |
| Answer» C. depend on direction | |
| 1321. |
Which of the following antenna is best guided by a waveguide? |
| A. | Biconical |
| B. | Horn |
| C. | Helical |
| D. | Dish |
| Answer» C. Helical | |
| 1322. |
Poynting vector is the rate of energy flow having |
| A. | W/m |
| B. | <sup>2</sup> |
| C. | W-m |
| D. | kWh/s |
| E. | W/m |
| Answer» B. <sup>2</sup> | |
| 1323. |
A hertzian dipole has a radiation pattern with |
| A. | a null in the direction of the dipole |
| B. | a null in the plane perpendicular to the dipole |
| C. | a peak in the direction of the dipole |
| D. | none of the above |
| Answer» B. a null in the plane perpendicular to the dipole | |
| 1324. |
Circular polarized waves result when |
| A. | magnitudes are the same |
| B. | phases are the same |
| C. | magnitudes are same and phase difference is 90 |
| D. | magnitudes are same and phase difference is zero |
| Answer» D. magnitudes are same and phase difference is zero | |
| 1325. |
Long distance short-wave radio broadcasting uses |
| A. | ground wave |
| B. | ionospheric wave |
| C. | direct wave |
| D. | any of the above |
| Answer» C. direct wave | |
| 1326. |
Which of following antenna not produces circular polarisation? |
| A. | Helical |
| B. | Parabolic |
| C. | Disc |
| D. | Yagi |
| Answer» E. | |
| 1327. |
The affect of ground on radiation pattern is to |
| A. | cause cancellation of radiation along the ground |
| B. | produce more number of nulls |
| C. | both (a) and (b) |
| D. | either (a) or (b) |
| Answer» D. either (a) or (b) | |
| 1328. |
The curve representing Ohm's law is |
| A. | linear |
| B. | a parabola |
| C. | a hyperbola |
| D. | sine function |
| Answer» B. a parabola | |
| 1329. |
When a plane wave is incident normally from dielectric '1' ( 0, 1) onto dielectric '2' ( 0, 2) the electric field of the transmitted wave is 2 times the electric field of the reflected wave. The ratio 2/ 1 is |
| A. | 0.5 |
| B. | 1 |
| C. | 2 |
| D. | 4 |
| Answer» E. | |
| 1330. |
Purpose of antenna is |
| A. | to transmit and receive energy |
| B. | to convert EM into electrical |
| C. | to convert electrical into EM |
| D. | all of the above |
| Answer» E. | |
| 1331. |
An open coil has |
| A. | zero resistance and inductance |
| B. | zero resistance and high inductance |
| C. | infinite resistance and zero inductance |
| D. | infinite resistance and normal inductance |
| Answer» D. infinite resistance and normal inductance | |
| 1332. |
Antenna used for direction finding is |
| A. | long dipole |
| B. | parabolic |
| C. | rhombic |
| D. | helical |
| Answer» B. parabolic | |
| 1333. |
In E plane metal plate lens antenna |
| A. | travelling wavefronts are retarded |
| B. | travelling wavefront are accelerated |
| C. | travelling wavefront remains unaffected |
| D. | none of the above |
| Answer» C. travelling wavefront remains unaffected | |
| 1334. |
The disturbance from adjacent telephone line is known as |
| A. | cross fire |
| B. | cross talk |
| C. | inductive disturbance |
| D. | none of the above |
| Answer» C. inductive disturbance | |
| 1335. |
The gain of a current element is |
| A. | 0 dB |
| B. | 1.67 dB |
| C. | 1.76 dB |
| D. | 3 dB |
| Answer» D. 3 dB | |
| 1336. |
The gain of an antenna with a circular aperture of diameter 3 metres at a frequency of 5 GHz, will be |
| A. | 2.4674 |
| B. | 24.674 |
| C. | 246.74 |
| D. | 24674 |
| Answer» E. | |
| 1337. |
Poynting theorem relates the electric intensity E, magnetic intensity H to the rate of energy flow per unit area at a point P as |
| A. | P = E/H |
| B. | P = H/E |
| C. | E = 1/E x H |
| D. | P = E x H |
| Answer» E. | |
| 1338. |
300 to 3000 MHz frequency is categorized as |
| A. | MF |
| B. | HF |
| C. | UHF |
| D. | SHF |
| Answer» D. SHF | |
| 1339. |
The absorption of EM wave by the atmosphere depends on |
| A. | polarization of waves |
| B. | frequency in use |
| C. | dist. from T |
| D. | <sub><i>y</i></sub> |
| E. | height of antenna |
| Answer» C. dist. from T | |
| 1340. |
When a coil consisting of single turn rotates at a uniform speed in a magnetic field, the induced e.m.f. is |
| A. | changing |
| B. | reversing |
| C. | steady |
| D. | alternating |
| Answer» E. | |
| 1341. |
Short-circuited stubs are used, because open-circuited stubs are |
| A. | liable to radiate |
| B. | complex in nature |
| C. | providing open-circuit environments |
| D. | unable to provide work over large frequency range |
| Answer» B. complex in nature | |
| 1342. |
An arrangement of several individual antennas to spaced and phased that their individual contributions combine in one preferred direction and cancel in all other directions, to get greater directive gain or directivity, is known as |
| A. | directional radiation of antennas |
| B. | antenna gain stability |
| C. | array of antennas |
| D. | none of the above |
| Answer» D. none of the above | |
| 1343. |
In order to receive a vertically polarized wave, the conductor of the dipole should be mounted |
| A. | horizontally |
| B. | vertically |
| C. | at an angle of 45 |
| D. | none of the above |
| Answer» C. at an angle of 45 | |
| 1344. |
Which of the following statements is incorrect? |
| A. | The line integral of B around the circuit is called magnetomotive force |
| B. | Normal components of B are continuous but the normal components of H are not continuous |
| C. | Magnetic flux lines are bent away from the normal in the medium with the highest value of permeability |
| D. | The unit of permeability is henry/metre |
| Answer» B. Normal components of B are continuous but the normal components of H are not continuous | |
| 1345. |
Reflectors and lens antennas are commonly used |
| A. | in LF communication systems |
| B. | not beyond 100 kHz |
| C. | in the range 10 MHz to 100 MHz |
| D. | above 100 MHz |
| Answer» E. | |
| 1346. |
In case of concentric conductors of radius a and b the value of capacitance (C) is given by |
| A. | C = 0 |
| B. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/193-166-1.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/193-166-2.png"> |
| D. | none of the above |
| Answer» D. none of the above | |
| 1347. |
Which one of the following statement is correct? |
| A. | Both Laplace's (L) and Poisson's (P) equation are non linear |
| B. | L is non linear but P is linear |
| C. | L is linear but P is non linear |
| D. | L, P both is linear |
| Answer» B. L is non linear but P is linear | |
| 1348. |
Frequency band used for radar is generally |
| A. | VLF |
| B. | VHF |
| C. | UHF |
| D. | EHF |
| Answer» D. EHF | |
| 1349. |
One volt equals |
| A. | one joule |
| B. | one joule/coulomb |
| C. | one coulomb/joule |
| D. | none of the above |
| Answer» D. none of the above | |
| 1350. |
In case of antenna the lower value of Q indicates |
| A. | higher bandwidth |
| B. | lower bandwidth |
| C. | higher distortion |
| D. | lower distortion |
| Answer» B. lower bandwidth | |