MCQOPTIONS
Saved Bookmarks
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.
| 201. |
A parametric amplifier uses |
| A. | non linear resistance |
| B. | non linear reactance |
| C. | either (a) or (b) |
| D. | neither (a) nor (b) |
| Answer» C. either (a) or (b) | |
| 202. |
Power monitor and reflectometer use the principle of |
| A. | an inductance |
| B. | a capacitance |
| C. | L and C in series |
| D. | L and C in parallel |
| Answer» B. a capacitance | |
| 203. |
In TE mode of waveguide Ez = 0 |
| A. | 1 |
| B. | |
| C. | R and L |
| D. | R, L and C |
| Answer» B. | |
| 204. |
In which mode of rectangular waveguide are all field components zero? |
| A. | TM00 |
| B. | TM11 |
| C. | TM01 |
| D. | TM10 |
| Answer» B. TM11 | |
| 205. |
If a line is open circuited Zin = Z0 tanh (gl). |
| A. | 1 |
| B. | |
| C. | one cavity resonator |
| D. | two cavity resonators |
| Answer» C. one cavity resonator | |
| 206. |
A balun should have |
| A. | low SWR at both ports |
| B. | high SWR at both ports |
| C. | high SWR at input port and low SWR at output port |
| D. | low SWR at input port and high SWR at output |
| Answer» B. high SWR at both ports | |
| 207. |
Impedance inversion may be obtained with |
| A. | a short circuited stub |
| B. | a quarter wave line |
| C. | an open circuited stub |
| D. | a half wave line |
| Answer» C. an open circuited stub | |
| 208. |
Consider the following time parameters Domain growth time constant.Transit time.Dielectric relaxation time in positive mobility regime. Which of the above are used in connection width transferred electron device? |
| A. | p+ and n layers separated by i layer |
| B. | p+ and n+ layers separated by i layer |
| C. | p- and n- layers separated by i layer |
| D. | none of the above |
| Answer» B. p+ and n+ layers separated by i layer | |
| 209. |
At a frequency equal to cutoff frequency in a rectangular wave guide |
| A. | the flow of electromagnetic energy is 50% of maximum |
| B. | the flow of electromagnetic energy is 10% of maximum |
| C. | 8, 4, 2, 2, 0 mW |
| D. | 0, 8, 4, 4, 0 mW |
| Answer» C. 8, 4, 2, 2, 0 mW | |
| 210. |
The radiation resistance of a circular loop of one turn is 0.01 ohm. For 5 turn loop the radiation resistance is |
| A. | 0.002 Ω |
| B. | 0.01 Ω |
| C. | 0.05 Ω |
| D. | 0.25 Ω |
| Answer» E. | |
| 211. |
In a vacuum tube, the transit time of electron between cathode and anode is important at |
| A. | low frequencies |
| B. | high frequencies |
| C. | both (a) and (b) |
| D. | frequencies which are neither very low nor very high |
| Answer» C. both (a) and (b) | |
| 212. |
A TEM wave is incident normally on a perfect conductor. The E and H fields at boundary will respectively be |
| A. | minimum and maximum |
| B. | minimum and minimum |
| C. | maximum and minimum |
| D. | maximum and maximum |
| Answer» B. minimum and minimum | |
| 213. |
The main advantage of TWT over klystron is |
| A. | higher bandwidth |
| B. | higher gain |
| C. | higher frequency |
| D. | higher output |
| Answer» B. higher gain | |
| 214. |
A microstrip line has ‚ààr = 9. The normalised wavelength is about |
| A. | 10 |
| B. | 2 |
| C. | 1 |
| D. | 0.4 |
| Answer» E. | |
| 215. |
A magnetron has a cylindrical cathode surrounded by an anode structure having cavities opening into interaction space by means of slots |
| A. | 1 |
| B. | |
| C. | anode, catcher cavity, cathode, buncher cavity |
| D. | cathode, buncher cavity, catcher cavity, cavity |
| Answer» B. | |
| 216. |
In a loss less line the propagation constant is equal to |
| A. | jωLC |
| B. | LC |
| C. | an infinite impedance in shunt with line |
| D. | an infinite impedance in series with line |
| Answer» B. LC | |
| 217. |
The total field developed by an antenna array at a distant point is |
| A. | phasor sum of fields produced by individual antennas of the array |
| B. | algebraic sum of fields produced by individual antennas of the array |
| C. | either (a) or (b) depending on type of array |
| D. | neither (a) nor (b) |
| Answer» B. algebraic sum of fields produced by individual antennas of the array | |
| 218. |
Assertion (A): Klystron amplifiers use one or more intermediate cavities in addition to buncher and catcher cavity.Reason (R): When one or more intermediate cavities are used the bandwidth can be increased. |
| 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 | |
| 219. |
In fibre optics the use is made of thin glass fibres for efficient transmission of light. |
| A. | 1 |
| B. | |
| C. | their magnitudes are equal |
| D. | their magnitudes are equal and they differ in phase by ± 90° |
| Answer» B. | |
| 220. |
Which one of the following is true for EM wave propagation through rectangular waveguide of cross-section 2a x a |
| A. | critical wavelength for TE10 mode is the same as that for TM10 mode |
| B. | critical wavelength for TE10 mode is double that for TE01mode |
| C. | 30 V |
| D. | -30 V |
| Answer» D. -30 V | |
| 221. |
If load impedance ZL >> Z0, then |
| A. | Z0 = ZL (VSWR) |
| B. | ZL = Z0 (VSWR) |
| C. | ZL = Z0 (VSWR - 1) |
| D. | ZL = Z0 VSWR |
| Answer» C. ZL = Z0 (VSWR - 1) | |
| 222. |
Which of these statements is correct? |
| A. | Ridge guide is essentially a form of capacitively loaded guide. |
| B. | Ridge guide is essentially a form of inductively loaded guide. |
| C. | Ridge guide is essentially a form of resistively loaded guide. |
| D. | Ridge guide has higher power handling capacity than rectangular waveguide. |
| Answer» B. Ridge guide is essentially a form of inductively loaded guide. | |
| 223. |
In a loss line RL < Z0, then |
| A. | Reflection coefficient is zero |
| B. | Reflection coefficient is ‚àû |
| C. | Reflection coefficient is negative |
| D. | Reflection coefficient is positive |
| Answer» D. Reflection coefficient is positive | |
| 224. |
In Gunn diode electrons are transferred from |
| A. | valley to domain formation |
| B. | domain to valley formation |
| C. | All |
| D. | 1 and 2 only |
| Answer» B. domain to valley formation | |
| 225. |
Assertion (A): The velocity of electromagnetic waves on overhead lines and coaxial cables is the same.Reason (R): Free space has an intrinsic impedance of 377 ohms. |
| A. | The radial lines are E lines and circular lines are H lines |
| B. | Radial lines are H lines and circular lines are E lines |
| C. | The directions of E and H lines are wrong |
| D. | Radial lines may be E and H lines depending an direction of current |
| Answer» E. | |
| 226. |
Assertion (A): In the interaction region of magnetron an electron is subjected to three forces: force due to electric field, force due to magnetic field and centrifugal force.Reason (R): The mechanism of generation of microwaves, in a magnetron, involves interaction of electromagnetic fields with electrons moving in static electric and magnetic fields oriented at right angles to each other. |
| 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 | |
| 227. |
At frequencies of 10 MHz and higher the impedance represented by ground is primarity |
| A. | resistive |
| B. | inductive |
| C. | capacitive |
| D. | partly resistive and partly capacitive |
| Answer» D. partly resistive and partly capacitive | |
| 228. |
A directional coupler is used to determine |
| A. | rv |
| B. | rv and VSWR |
| C. | L and C |
| D. | wave velocity |
| Answer» C. L and C | |
| 229. |
When a line short circuited at far end, the minimum voltage occurs at |
| A. | midway between source and far end |
| B. | none of the above |
| C. | at a velocity that is almost equal to speed of light |
| D. | at a velocity that is a small fraction of speed of light |
| Answer» B. none of the above | |
| 230. |
A line of characteristic impedance Z0 branches into two line each with characteristic impedance Z0. The refracted voltage is |
| A. | zero |
| B. | infinite |
| C. | equal to incident voltage |
| D. | two third of incident voltage |
| Answer» E. | |
| 231. |
A duplexer is used to |
| A. | couple two antennas to a transmitter |
| B. | isolate the antenna from the local oscillator |
| C. | prevent interference between two antennas connected to receiver |
| D. | use an antenna for reception or transmission without interference |
| Answer» E. | |
| 232. |
In a rectangular waveguide there is one half wave variation of electric field across the narrow dimension and two half wave variations of electric field across wider dimension. The dominant mode is |
| A. | TM12 |
| B. | TE13 |
| C. | TE21 |
| D. | TM25 |
| Answer» D. TM25 | |
| 233. |
Consider the following statements Gunn diode can be used in combinational logic circuits.Gunn diode can be used in sequential logic circuits.Both Gunn diode and GaAs Mesfet can be used in logic circuits. Which of the above statements are correct? |
| A. | 1, 2, and 3 |
| B. | 1 and 2 only |
| C. | 2 and 3 only |
| D. | 1 and 3 only |
| Answer» B. 1 and 2 only | |
| 234. |
The earliest uses of electromagnetic waves were |
| A. | both (a) and (b) |
| B. | neither (a) nor (b) |
| C. | TE01 |
| D. | TE11 |
| Answer» D. TE11 | |
| 235. |
VSWR = Emax/Emin. |
| A. | directional coupler |
| B. | klystron amplifier |
| C. | Gunn diode |
| D. | TWT |
| Answer» B. klystron amplifier | |
| 236. |
Assertion (A): For a reciprocal microwave junction the S matrix is symmetrical.Reason (R): In a symmetrical matrix Sij = Sji. |
| 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 | |
| 237. |
In directional coupler of the given figure, the terms |S14| and |S23| of scattering matrix are nearly |
| A. | 0.1 each |
| B. | 1 and 0.5 respectively |
| C. | 100 MHz |
| D. | 50 MHz |
| Answer» B. 1 and 0.5 respectively | |
| 238. |
A line has an attenuation of 0.054 Np/m. The attenuation in decibels is |
| A. | 4.7 dB/m |
| B. | 0.47 dB/m |
| C. | 0.54 dB/m |
| D. | 5.4 dB/m |
| Answer» C. 0.54 dB/m | |
| 239. |
In a multicavity klystron amplifier the electron velocity of the order of |
| A. | 106 m/s |
| B. | 1012 m/s |
| C. | the flow of electromagnetic energy is zero |
| D. | the flow of electromagnetic energy is infinite |
| Answer» D. the flow of electromagnetic energy is infinite | |
| 240. |
To study electromagnetic radiations from astronomical objects, radio astronomers use |
| A. | low frequencies |
| B. | medium frequencies |
| C. | microwaves |
| D. | either (a) or (b) |
| Answer» D. either (a) or (b) | |
| 241. |
Assertion (A): PIN diode is commonly used for microwave control.Reason (R): A PIN diode uses heavily doped p and n materials. |
| 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 | |
| 242. |
Assertion (A): The condition of minimum distortion in a transmission line is L = RC/G.Reason (R): Line loading means addition of inductance to satisfy the condition L = RC/G. |
| 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 | |
| 243. |
Which mode has the minimum cutoff frequency in rectangular wave guides? |
| A. | TE11 |
| B. | TE10 |
| C. | TE01 |
| D. | TE20 |
| Answer» C. TE01 | |
| 244. |
Z0 = (Zoc Zsc)0.5 |
| A. | 1 |
| B. | |
| C. | has all diagonal elements zero |
| D. | has all diagonal elements equal but not zero |
| Answer» B. | |
| 245. |
In microstrip line has dielectric material most commonly used is |
| A. | silicon |
| B. | rubber |
| C. | plastic |
| D. | bakelite |
| Answer» B. rubber | |
| 246. |
The noise figure of klystron amplifier is about |
| A. | zero |
| B. | 1 dB |
| C. | critical wavelength for TE10 mode is the same as that for TE02 mode |
| D. | critical wavelength for TE10 mode is one half of that for TE10 mode |
| Answer» B. 1 dB | |
| 247. |
Read the following statements about TWT It uses thermionic emission.It uses an attenuater.It is inherently a resonant device.It has broad bandwidth. Which of the above are correct? |
| A. | 1, 2, 3 and 4 |
| B. | 1, 2 and 3 |
| C. | 1, 3 and 4 |
| D. | 1, 2 and 4 |
| Answer» E. | |
| 248. |
In a klystron amplifier the force on all electrons |
| A. | causes acceleration of all electrons |
| B. | causes retardation of all electrons |
| C. | causes acceleration of some electrons and retardation of others |
| D. | none of the above |
| Answer» D. none of the above | |
| 249. |
In the given figure the circuits for input impedance of a microwave device with output ports match terminated. The device is |
| A. | E plane tee |
| B. | H plane tee |
| C. | magic tee |
| D. | hybrid ring |
| Answer» E. | |
| 250. |
Which of the following are true for magic tee in the given figure select the answer as per given codes S13 = S23S14 = S24S12 = 0S34 = 0 |
| A. | 2, 3 and 4 |
| B. | 1, 3 and 4 |
| C. | photoetching technique |
| D. | oxidation technique |
| Answer» D. oxidation technique | |