MCQOPTIONS
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MCQOPTIONS
This section includes 551 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 251. |
As regards rectangular and circular waveguides |
| A. | both have infinite set of TE and TM modes |
| B. | rectangular waveguide has infinite TE and TM modes but not the circular waveguide |
| C. | circular waveguide has infinite TE and TM modes but not the rectangular waveguide |
| D. | none of the above |
| Answer» B. rectangular waveguide has infinite TE and TM modes but not the circular waveguide | |
| 252. |
In microwave system, waveguide twists |
| A. | change the plane of polarization of a propagating wave |
| B. | change the direction of a propagating wave |
| C. | change the mode of a propagating wave |
| D. | both (b) and (c) |
| Answer» B. change the direction of a propagating wave | |
| 253. |
Radar is essentially an echo ranging system |
| A. | 1 |
| B. | |
| C. | Ridge guide is essentially a form of capacitively loaded guide |
| D. | low to high mobility energy bands |
| Answer» B. | |
| 254. |
Assertion (A): In circular waveguide the attenuation of TE01 mode decreases as the operating frequency increases.Reason (R): The wall currents in a circular waveguide in TEQ1 mode are completely circumferential. |
| 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 | |
| 255. |
The noise figure of multicavity klystron amplifier is very low |
| 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 | |
| 256. |
Standard mismatches are used to calibrate SWR and impedance measuring equipments. |
| A. | 1 |
| B. | |
| C. | 1, 2, 3 are correct |
| D. | 1, 2, 4 are correct |
| Answer» B. | |
| 257. |
A pulsed radar produces 1 μ sec pulses at a rate of 1000 per second. The duty cycle is |
| A. | 0.001 |
| B. | 0.01 |
| C. | 0.1 |
| D. | 1 |
| Answer» B. 0.01 | |
| 258. |
A magnetron requires an external magnetic field with flux lines parallel to axis of cathode |
| A. | 1 |
| B. | |
| C. | far end |
| D. | source end |
| Answer» B. | |
| 259. |
In a rectangular waveguide |
| A. | any one of the dimensions may be labelled 'a' and the other 'b' |
| B. | the length is labelled as 'a' |
| C. | TE110 |
| D. | TE011 |
| Answer» B. the length is labelled as 'a' | |
| 260. |
A radar has a maximum range of 120 km. The maximum allowable pulse repetition frequency for unambiguous reception is |
| A. | 1250 |
| B. | 330 |
| C. | 2500 |
| D. | 8330 |
| Answer» B. 330 | |
| 261. |
As frequency is increased, the skin effect |
| A. | increases |
| B. | decreases |
| C. | remains the same |
| D. | either (b) or (c) |
| Answer» B. decreases | |
| 262. |
In a circular waveguide with radius r, the dominant mode is |
| A. | TM01 |
| B. | TE01 |
| C. | TM11 |
| D. | TE11 |
| Answer» C. TM11 | |
| 263. |
The AM, PM, and TV broadcast frequencies are |
| A. | of the same order as microwave range |
| B. | much lower than microwave range |
| C. | much higher than microwave range |
| D. | either (a) or (c) |
| Answer» C. much higher than microwave range | |
| 264. |
The first and second subscripts in models of circular waveguides depict |
| A. | the number of full sine wave variations in circumference in direction and Bessel function variations in radial direction respectively |
| B. | the Bessel function variations in radial direction and the number of full sine wave variations in circumference direction respectively |
| C. | the Bessel function variations in circumference direction and number of full sine wave variations in radial direction respectively |
| D. | none of the above |
| Answer» B. the Bessel function variations in radial direction and the number of full sine wave variations in circumference direction respectively | |
| 265. |
In a reflex klystron oscillator, repeller electrode is at |
| A. | low positive potential |
| B. | high positive potential |
| C. | negative potential |
| D. | zero potential |
| Answer» D. zero potential | |
| 266. |
The main advantage of using micro waves for communications is |
| A. | large bandwidth |
| B. | small bandwidth |
| C. | low power |
| D. | high power |
| Answer» B. small bandwidth | |
| 267. |
Assertion (A): A small section of high impedance line is equivalent to a series inductance.Reason (R): A small section of a low impedance line is equivalent to a series resistance. |
| A. | A is correct but R is wrong |
| B. | A is wrong but R is correct |
| C. | Both A and R are correct and R is correct explanation of A |
| D. | Both A and R are correct but R is not correct explanation of A |
| Answer» D. Both A and R are correct but R is not correct explanation of A | |
| 268. |
Assertion (A): A quarter wave transformer is used to match a resistive load to a transmission line.Reason (R): A quarter wave transformer is a transmission line of quarter wave length. |
| 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 | |
| 269. |
Assertion (A): Slotted line is frequently used for microwave measurements.Reason (R): The unknown impedance is mounted at the end of slotted line. |
| 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 | |
| 270. |
Consider the following applications TV tuningActive filterMicrowave frequency multiplication In which of above can a varactor diode be used? |
| A. | 1 2 and 3 |
| B. | l and 2 only |
| C. | 1 and 3 only |
| D. | 2 and 3 only |
| Answer» B. l and 2 only | |
| 271. |
Consider the following statements about directional coupler shown in the figure Ports 1 and 2 are decouplePorts 3 and 4 are decoupledPots 1 and 3 are decoupledPorts 1 and 4 are decoupled Which of the above statements are correct? |
| A. | 1, 2 and 3 |
| B. | 2, 3 and 4 |
| C. | 10 m/s |
| D. | 103 m/s |
| Answer» B. 2, 3 and 4 | |
| 272. |
The main feature of a parametric amplifier is |
| A. | low noise |
| B. | very high gain |
| C. | broad bandwidth |
| D. | both (b) and (c) |
| Answer» D. both (b) and (c) | |
| 273. |
In a coaxial line |
| A. | the characteristic impedance is less than that of two wire line |
| B. | the wave velocity is less than that of two wire line |
| C. | both (a) and (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 274. |
Assertion (A): In TE mode for rectangular waveguide.Reason (R): In TM mode for rectangular waveguide. |
| 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 | |
| 275. |
In microwave system the function of mode filter is |
| A. | to suppress modes with lower cut off frequencies |
| B. | to suppress modes with higher cut off frequencies |
| C. | to change mode of wave transmission |
| D. | both (b) and (c) |
| Answer» E. | |
| 276. |
For a directional coupler the power is in the ratio of |
| A. | 40 dB |
| B. | 30 dB |
| C. | 20 dB |
| D. | 10 dB |
| Answer» D. 10 dB | |
| 277. |
If D is diameter of circular waveguide the cutoff wave-length for TE11 mode is equal to |
| A. | 0.82 D |
| B. | 0.41 D |
| C. | parallel to the axis of cathode |
| D. | perpendicular to the axis of cathode |
| Answer» B. 0.41 D | |
| 278. |
TM01 mode in circular waveguide is analogous to |
| A. | TM10 mode in square waveguide |
| B. | TM11 mode in square waveguide |
| C. | TM20 mode in square waveguide |
| D. | TM02 mode in square waveguide |
| Answer» C. TM20 mode in square waveguide | |
| 279. |
Microwave links are typically 50 km apart |
| A. | because of atmospheric attenuation |
| B. | because of output tube power limitation |
| C. | because of earth's curvature |
| D. | to ensure that applied dc voltage is not excessive |
| Answer» D. to ensure that applied dc voltage is not excessive | |
| 280. |
Generally the wall thickness of rectangular waveguide is |
| A. | about 1-5 mils |
| B. | about 40-100 mils |
| C. | about 0.1 to 0.5 mils |
| D. | about 500 mils |
| Answer» C. about 0.1 to 0.5 mils | |
| 281. |
As frequency increases, the transmission efficiency |
| A. | decreases |
| B. | increases |
| C. | is not affected |
| D. | either (a) or (c) |
| Answer» C. is not affected | |
| 282. |
Effect of loading of line is |
| A. | increase in Z0, a and β |
| B. | increase in Z0 and β but decrease in a |
| C. | decrease in Z0, a and β |
| D. | decrease in Z0 and β but increase in a |
| Answer» C. decrease in Z0, a and Œ≤ | |
| 283. |
Assertion (A): In rectangular waveguide TE01 mode is just TE10 mode rotated by 90°.Reason (R): When a rectangular waveguide is rotated by 90°, the broad and narrow dimensions get interchanged. |
| 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 | |
| 284. |
The word 'LORAN' means |
| A. | long range navigation |
| B. | long range TV transmission |
| C. | long range cable transmission |
| D. | either (b) or (c) |
| Answer» B. long range TV transmission | |
| 285. |
In a TWT the loss in attenuator is |
| A. | almost equal to forward gain of tube |
| B. | much less than forward gain of tube |
| C. | much higher than forward gain of tube |
| D. | almost infinite |
| Answer» B. much less than forward gain of tube | |
| 286. |
A line of characteristic impedance 400 Ω is terminated by a resistance of 400 Ω. The reflected quantities are |
| A. | zero |
| B. | equal to incident quantities |
| C. | half the incident quantities |
| D. | double the incident quantities |
| Answer» B. equal to incident quantities | |
| 287. |
Which of the following modes cannot exist in rectangular resonant cavity? |
| A. | TE110 |
| B. | TE011 |
| C. | TM110 |
| D. | TM111 |
| Answer» B. TE011 | |
| 288. |
In a TWT the phase velocity of the axial component of the field on the slow wave structure is kept |
| A. | equal to velocity of electron |
| B. | slightly less than velocity of electron |
| C. | slightly more than velocity of electron |
| D. | equal to velocity of light in free space |
| Answer» B. slightly less than velocity of electron | |
| 289. |
The effect of earth's magnetic field on radiowaves is minimum when |
| A. | the electric field lines of radio waves and flux line of earth's magnetic field are in the same direction |
| B. | the electric field lines of radio waves and flux lines of earth's magnetic field are at right angles |
| C. | the electric field lines of radiowaves and flux lines of earth's magnetic field oppose each other |
| D. | both (b) and (c) |
| Answer» B. the electric field lines of radio waves and flux lines of earth's magnetic field are at right angles | |
| 290. |
The following components are used to measure power output of a 2 kW TWT amplifier TWTLow pass/High pass filterLow power 20 dB attenuator40 dB directional coupler with matched loadPower meter. The correct sequence of connections of these components is: |
| A. | 1, 4, 2, 3, 5 |
| B. | 1, 3, 4, 2, 5 |
| C. | 1, 2, 4, 3, 5 |
| D. | 1, 4, 3, 2, 5 |
| Answer» C. 1, 2, 4, 3, 5 | |
| 291. |
Assertion (A): Hollow waveguides are frequently used as transmission lines at microwave frequencies.Reason (R): Waveguide has high power handling capacity, low loss and simple structure. |
| 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 | |
| 292. |
If the peak transmitted power in a radar is increased by a factor 81, the maximum range is increased by a factor of |
| A. | 3 |
| B. | 9 |
| C. | 27 |
| D. | 81 |
| Answer» B. 9 | |
| 293. |
A rectangular wave guide has two stubs each of length connected at the source end. The stubs are circuited. Then the stubs present |
| A. | an infinite impedance in shunt with line |
| B. | an infinite impedance in series with line |
| C. | a zero impedance in shunt with line |
| D. | a finite impedance in shunt with line |
| Answer» B. an infinite impedance in series with line | |
| 294. |
Assertion (A): Impedance measurement at microwave frequencies is done by finding SWR.Reason (R): SWR and reflection coefficient depend on the characteristic impedance and load impedance. |
| 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 | |
| 295. |
Integrated fin line can be utilized as a medium for constructing millimeter wave circuits. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 296. |
Assertion (A): Magnetron is generally used in n mode.Reason (R): Frequency for p mode can be easily separated from adjacent modes. |
| 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 | |
| 297. |
The inductance of a twin feeder used to connect antenna to TV receiver is about |
| A. | 0.2 μ H/m |
| B. | 0.6 μ H/m |
| C. | 1.6 μ H/m |
| D. | 10 μ H/m |
| Answer» D. 10 Œº H/m | |
| 298. |
In a high frequency coaxial line and the length of line characteristic impedance is a function of |
| A. | properties of insulating material only |
| B. | inner and outer conductor radius only |
| C. | both (a) and (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 299. |
In an infinite line the input impedance at every point is equal to characteristic impedance. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 300. |
Assertion (A): An artificial transmission line can be used as a pulse generator.Reason (R): A pulse function is used very frequently in network analysis. |
| 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 | |