MCQOPTIONS
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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.
| 9251. |
Impedance level of Impatt diodes is generally lower than that of Gunn diodes |
| A. | True |
| B. | False |
| Answer» B. False | |
| 9252. |
A quarter wave line open circuited at far end behaves as |
| A. | inductance |
| B. | L and C in parallel |
| C. | capacitance |
| D. | L and C in series |
| Answer» E. | |
| 9253. |
Which of the following is taken as reference antenna for directive gain? |
| A. | Half wave dipole |
| B. | Elementary doublet |
| C. | Isotropic |
| D. | Infinitesimal dipole |
| Answer» D. Infinitesimal dipole | |
| 9254. |
Push pull amplifier is |
| A. | voltage amplifier |
| B. | current amplifier |
| C. | power amplifier |
| D. | none of the above |
| Answer» D. none of the above | |
| 9255. |
When the channel is noisy, producing a conditional probability of error p = 0.5; the channel capacity and entropy function would be, respectively, |
| A. | 1 and 1 |
| B. | 1 and 0.5 |
| C. | 0.5 and 1 |
| D. | 0 and 1 |
| Answer» E. | |
| 9256. |
In CCIR-B system, the time between start of one H syn. pulse and next is |
| A. | 64 s |
| B. | 6.4 s |
| C. | 640 s |
| D. | 0.64 s |
| Answer» B. 6.4 s | |
| 9257. |
Counterpoise is used in coils having |
| A. | high resistivity |
| B. | low resistivity |
| C. | medium resistivity |
| D. | both (b) and (c) |
| Answer» B. low resistivity | |
| 9258. |
The fabrication of microstrip line is done by |
| A. | photo etching |
| B. | printed circuit technique |
| C. | oxidation |
| D. | cladding |
| Answer» C. oxidation | |
| 9259. |
The condition of minimum distortion in a transmission line is |
| A. | RL = 1 |
| B. | R = 0 |
| C. | <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/09-22-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/09-22-4.png"> |
| Answer» E. | |
| 9260. |
In a travelling wave tube distributed interaction between an electron beam and a travelling wave takes place |
| A. | True |
| B. | False |
| Answer» B. False | |
| 9261. |
A line has Z0 = 300 0 . If ZL = 150 0 , reflection coefficient is |
| A. | 0.5 |
| B. | 0.3333 |
| C. | -0.3333 |
| D. | -0.5 |
| Answer» D. -0.5 | |
| 9262. |
In a microstrip transmission the signal can be easily redirected by changing the centre strip. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 9263. |
The frequency of oscillation in a backward wave oscillator can be changed by |
| A. | varying the voltage which controls beam velocity |
| B. | varying the beam current |
| C. | both by varying the beam current and by light varying the voltage which controls beam velocity |
| D. | changing the rate of thermionic emission |
| Answer» B. varying the beam current | |
| 9264. |
A line has a phase constant of 29.8 rad/m. At 1000 MHz the wavelength is |
| A. | 29.8 m |
| B. | 2.98 m |
| C. | 2.1 m |
| D. | 0.21 m |
| Answer» E. | |
| 9265. |
Assertion (A): A backward wave oscillator has an internal positive feedback.Reason (R): A positive feedback is necessary for sustained oscillations. |
| 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 | |
| 9266. |
In sound recording the degree of pre-emphasis is about 6 dB/ octave. |
| A. | True |
| B. | False |
| Answer» C. | |
| 9267. |
Space wave may be a direct wave or wave reflected from earth. |
| A. | True |
| B. | False |
| Answer» C. | |
| 9268. |
Radio broadcasts are generally |
| A. | amplitude modulation |
| B. | frequency modulation |
| C. | both amplitude and frequency modulation |
| D. | neither amplitude nor frequency modulation |
| Answer» C. both amplitude and frequency modulation | |
| 9269. |
If the frequency of a wave 20 Hz, the time period is |
| A. | 20 secs |
| B. | 2 secs |
| C. | 0.2 secs |
| D. | 0.05 secs |
| Answer» E. | |
| 9270. |
Which of the following lines is non-radiating? |
| A. | Open two wire |
| B. | Coaxial |
| C. | Both |
| D. | None of the above |
| Answer» C. Both | |
| 9271. |
Assertion (A): The impedance of a matched load is equal to characteristic impedance of line.Reason (R): A matched termination absorbs all the power incident on it. |
| 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 | |
| 9272. |
Skin effect is more pronounced at high frequencies. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 9273. |
Assertion (A): The phenomenon of differential mobility is called transferred electron effect.Reason (R): GaAs exhibits transferred electron effect. |
| 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 | |
| 9274. |
Loss angle of a good quality cable is about |
| A. | 1 |
| B. | 30 |
| C. | 70 |
| D. | 90 |
| Answer» B. 30 | |
| 9275. |
In a three cavity klystron amplifier, the oscillations are excited in |
| A. | input cavity |
| B. | output cavity |
| C. | intermediate cavity |
| D. | both (a) and (b) |
| Answer» D. both (a) and (b) | |
| 9276. |
Which of the following devices uses a helix? |
| A. | Klystron amplifier |
| B. | Klystron oscillator |
| C. | TWT |
| D. | Both (a) and (b) |
| Answer» D. Both (a) and (b) | |
| 9277. |
In a directional coupler |
| A. | isolation (dB) equals coupling plus directivity |
| B. | coupling (dB) equals isolation plus directivity |
| C. | directivity (dB) equals isolation plus coupling |
| D. | isolation (dB) equals (coupling) (directivity) |
| Answer» B. coupling (dB) equals isolation plus directivity | |
| 9278. |
As the frequency is increased, the charging MVAR in a cable |
| A. | decreases |
| B. | increases |
| C. | remain the same |
| D. | decreases or remains the scheme |
| Answer» C. remain the same | |
| 9279. |
Assertion (A): A coaxial line is a non-radiating line.Reason (R): In a coaxial line the electric and magnetic fields are confined to the region between the concentric conductors. |
| 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 | |
| 9280. |
Reflex klystron oscillator is essentially a low power device |
| A. | True |
| B. | False |
| Answer» B. False | |
| 9281. |
A 10 km long line has a characteristic impedance of 400 ohms. If line length is 100 km, the characteristic impedance is |
| A. | 4000 |
| B. | 400 |
| C. | 40 |
| D. | 4 |
| Answer» C. 40 | |
| 9282. |
A matched generator (Zg = Z0) with 1 available. If all ports are matched, the power delivered at ports 1, 2, 3 respectively are |
| A. | 0.5 W, 0.5 W, 0 W |
| B. | 0 W, 0 W, 1 W |
| C. | 0.33 W each |
| D. | 0 W, 0.25 W, 0.25 W |
| Answer» B. 0 W, 0 W, 1 W | |
| 9283. |
The action of backward wave oscillator is similar to that of |
| A. | klystron amplifier |
| B. | reflex klystron oscillator |
| C. | TWT |
| D. | magnetron |
| Answer» D. magnetron | |
| 9284. |
In the given figure the reflection coefficient at source end is |
| A. | 1 |
| B. | -1 |
| C. | 1/3 |
| D. | -1/3 |
| Answer» D. -1/3 | |
| 9285. |
Assertion (A): Artificial transmission lines are frequently used in laboratories.Reason (R): An artificial transmission line can be used to represent an actual line and can also be used as a delay circuit, as attenuator, as filter network etc. |
| 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 | |
| 9286. |
A resistive microwave load with ZL = 150 is connected to 50 coaxial line. SWR is |
| A. | more than 3 |
| B. | less than 3 |
| C. | equal to 3 |
| D. | either (a) or (c) |
| Answer» D. either (a) or (c) | |
| 9287. |
Which of the following devices uses a slow wave structure? |
| A. | Klystron two cavity amplifier |
| B. | Klystron multicavity amplifier |
| C. | Reflex klystron oscillator |
| D. | TWT |
| Answer» E. | |
| 9288. |
In a turnstile antenna two-half wave resonant wire radiators are placed at 90 to each other in the same plane and are excited |
| A. | in phase |
| B. | in phase opposition |
| C. | 90 out of phase with each other |
| D. | 45 out of phase with each other |
| Answer» D. 45 out of phase with each other | |
| 9289. |
In the given figure reflection coefficient at load is |
| A. | 0.6 |
| B. | - 0.6 |
| C. | 0.4 |
| D. | - 0.4 |
| Answer» C. 0.4 | |
| 9290. |
In a backward wave oscillator the wave travelling along the line winds itself back and forth |
| A. | True |
| B. | False |
| Answer» B. False | |
| 9291. |
A line is excited by a 100 V dc source. If reflection coefficients at both ends are 1 each then |
| A. | there will be no oscillations on line |
| B. | there will be only 1 or 2 oscillations on line |
| C. | there will be a finite number of oscillations on line |
| D. | the oscillations will continue indefinitely |
| Answer» E. | |
| 9292. |
A waveguide section in a microwave circuit acts as |
| A. | LP filter |
| B. | Bandpass filter |
| C. | HP filter |
| D. | Band stop filter |
| Answer» D. Band stop filter | |