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.
| 401. |
Assertion (A): The velocity factor of a line is the ratio of wave velocity on the line to speed of light.Reason (R): If the conductors of a line are immersed in a non magnetic insulating liquid, the wave velocity increases. |
| 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» D. A is wrong but R is correct | |
| 402. |
The number of PM radio channels which can be accommodated in a spectrum of 300 MHz is about |
| A. | 10 |
| B. | 100 |
| C. | 500 |
| D. | 1500 |
| Answer» E. | |
| 403. |
Assertion (A): In a power divider SH = 0, S21 = 0.707 = S3, Reason (R): In a power divider the input port (i.e., port 1) is matched and incident power is equally divided in output ports 2 and 3 |
| 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 | |
| 404. |
A quarter wave line short circuited at load end behaves as |
| A. | an inductance |
| B. | an inductance and capacitance in series |
| C. | a capacitance |
| D. | an inductance and capacitance in parallel |
| Answer» E. | |
| 405. |
The manufacturing technique used to manufacture strip type transmission line is |
| A. | photoetching technique |
| B. | oxidation technique |
| C. | cladding |
| D. | epitaxial |
| Answer» B. oxidation technique | |
| 406. |
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 | |
| 407. |
When duct propagation exists |
| A. | the line of sight and diffraction. Zone concepts are payable |
| B. | the line of sight and diffraction zone concepts are not applicable |
| C. | line of sight concept is applicable but diffraction zone concept is applicable |
| D. | diffraction zone concept is not applicable but line of sight concept is not applicable |
| Answer» C. line of sight concept is applicable but diffraction zone concept is applicable | |
| 408. |
Which one of the following can be used for amplification of microwave energy? |
| A. | TWT |
| B. | Magnetron |
| C. | Reflex klystron |
| D. | Gunn diode |
| Answer» B. Magnetron | |
| 409. |
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 | |
| 410. |
Compared to coaxial lines, the advantages of wave guides are |
| A. | higher power handling capacity |
| B. | lower loss per unit length |
| C. | cheaper and simple mechanical structure |
| D. | all of the above |
| Answer» E. | |
| 411. |
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) | |
| 412. |
The rotation of direction of E field of a linearly polarized wave passing through a magnetised ferric medium is called |
| A. | Lorentz rotation |
| B. | Faraday rotation |
| C. | Steinmitz rotation |
| D. | Fleming's rotation |
| Answer» C. Steinmitz rotation | |
| 413. |
Assertion (A): PIN diode is used as a fast switch.Reason (R): PIN diode has very high resistance when reverse biased and very low resistance when forward biased. |
| 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 | |
| 414. |
In the given figure the reflection coefficient at source end is |
| A. | 1 |
| B. | -1 |
| C. | 43525 |
| D. | -0.333333333 |
| Answer» D. -0.333333333 | |
| 415. |
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 | |
| 416. |
Which one of the following is transferred locking electron device C antenna? |
| A. | BARITT diode |
| B. | IMPATT diode |
| C. | Gunn diode |
| D. | Step recovery diode |
| Answer» D. Step recovery diode | |
| 417. |
Ridge waveguide is essentially a form of capacitively loaded guide. |
| A. | 1 |
| B. | |
| C. | the broad width is generally labelled 'a' and height 'b' |
| D. | the broad width is generally labelled 'b' and height 'a' |
| Answer» B. | |
| 418. |
The arrangement in the given figure is a hybid T. If 100 mW fed at port 1, the power reflected back at port 1 is |
| A. | 0 |
| B. | 25 mW |
| C. | 50 mW |
| D. | 100 mW |
| Answer» D. 100 mW | |
| 419. |
The most commonly used magnetron is |
| A. | cylindrical |
| B. | parallel plate |
| C. | inclined plate |
| D. | flat plate |
| Answer» B. parallel plate | |
| 420. |
Assertion (A): Impatt diode is an avalanche diode.Reason (R): Avalanche breakdown phenomenon occurs when a p-n junction is reverse biased. |
| 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 | |
| 421. |
A coaxial RF cable has a characteristic impedance of 50 Ω and C equal to 40 pF/m. The inductance is |
| A. | 1 μ H/m |
| B. | 10 μ H/m |
| C. | 0.1 μ H/m |
| D. | 0.01 μ H/m |
| Answer» D. 0.01 Œº H/m | |
| 422. |
In mode filter of the given figure which of the following modes is unaffected |
| A. | TE01 |
| B. | TE10 |
| C. | TE11 |
| D. | all TM |
| Answer» B. TE10 | |
| 423. |
Assertion (A): PIN diode can be used as attenuator and limiter.Reason (R): PIN diode has a thin intrinsic layer. |
| 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 | |
| 424. |
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 | |
| 425. |
In the given figure power meters at A and B indicate 1 mW and 110 μW respectively. VSWR of line is |
| A. | 1.5 |
| B. | 2 |
| C. | 2.5 |
| D. | 3 |
| Answer» C. 2.5 | |
| 426. |
As compared to their values in free space |
| A. | velocity of electric wave in dielectric is smaller but wave length of electric wave is more |
| B. | both velocity and wave length of electric wave in dielectric are higher |
| C. | both velocity and wave length of electric wave in dielectric are smaller |
| D. | wave length of electric wave is less but velocity is more in dielectric |
| Answer» D. wave length of electric wave is less but velocity is more in dielectric | |
| 427. |
Radar principle is used in |
| A. | detection of aircraft |
| B. | burglar alarms |
| C. | garage door openers |
| D. | all of the above |
| Answer» E. | |
| 428. |
The cut off wavelength in circular waveguide |
| A. | guide diameter |
| B. | square of guide diameter |
| C. | cube of guide diameter |
| D. | square root of guide diameter |
| Answer» B. square of guide diameter | |
| 429. |
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. | |
| 430. |
Impedance level of Impatt diodes is generally lower than that of Gunn diodes |
| A. | 1 |
| B. | |
| Answer» B. | |
| 431. |
If a short line is terminated in characteristic impedance it behaves as an infinite line. |
| A. | 1 |
| B. | |
| C. | 1 |
| D. | |
| Answer» B. | |
| 432. |
The two terms used to describe performance of a directional coupler are |
| A. | coupling and directivity |
| B. | gain and coupling |
| C. | gain and directivity |
| D. | gain and isolation |
| Answer» B. gain and coupling | |
| 433. |
In TE10 mode the largest electric field in a rectangular wave guide, occurs |
| A. | along centre line of broad wall (i.e. x = a/2) |
| B. | along the broad wall (i.e. x = 0 and x = a) |
| C. | either (a) or (b) |
| D. | neither (a) nor (b) |
| Answer» B. along the broad wall (i.e. x = 0 and x = a) | |
| 434. |
The characteristic impedance of a cable is about |
| A. | 300 Ω |
| B. | 50 Ω |
| C. | 5 Ω |
| D. | 2 Ω |
| Answer» C. 5 Œ© | |
| 435. |
Satellite communication systems use the frequency band |
| A. | 10 to 20 MHz |
| B. | 50 to 70 MHz |
| C. | 3 to 6 GHz |
| D. | 100 to 120 GHz |
| Answer» D. 100 to 120 GHz | |
| 436. |
In a microwave resistor the wall thickness is made as small as possible to |
| A. | have high value of R |
| B. | have low value of R |
| C. | minimize capacitive effect |
| D. | reduce inductance |
| Answer» D. reduce inductance | |
| 437. |
A transmission line discontinuity is defined as any interruption in the uniformity of the line. |
| A. | 1 |
| B. | |
| C. | horizontally polarized |
| D. | vertically polarized |
| Answer» B. | |
| 438. |
Loss angle of a good quality cable is about |
| A. | 1° |
| B. | 30° |
| C. | 70° |
| D. | 90° |
| Answer» B. 30¬∞ | |
| 439. |
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 | |
| 440. |
Which of the following modes of transmission will not be supported by a rectangular waveguide? |
| A. | TE15 |
| B. | TE12 |
| C. | TM11 |
| D. | TM10 |
| Answer» E. | |
| 441. |
In a backward wave oscillator the wave travelling along the line winds itself back and forth |
| A. | 1 |
| B. | |
| Answer» B. | |
| 442. |
Frequency range for satellite communication is |
| A. | 1 kHz to 100 kHz |
| B. | 100 kHz to 10 MHz |
| C. | 10 MHz to 100 MHz |
| D. | 1 GHz to 30 GHz |
| Answer» E. | |
| 443. |
If a microstrip is enclosed in a metal enclosure |
| A. | the radiation losses are increased |
| B. | the radiation losses are reduced RL |
| C. | the capacitance becomes zero |
| D. | the inductance becomes zero |
| Answer» C. the capacitance becomes zero | |
| 444. |
The total power radiated from an antenna system is determined by imagining that the antenna is at the centre of a very large |
| A. | sphere |
| B. | rectangle |
| C. | square |
| D. | ellipse |
| Answer» B. rectangle | |
| 445. |
Which modes of circular wave guides have circular symmetry? |
| A. | TE11 |
| B. | TE11 and TE21 |
| C. | TE01 |
| D. | TE01 and TM01 |
| Answer» E. | |
| 446. |
In which of the following devices can the operation be visualised in terms of a series feedback loops? |
| A. | TWT |
| B. | Reflex klystron |
| C. | Klystron amplifier |
| D. | Backward wave oscillator |
| Answer» E. | |
| 447. |
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 | |
| 448. |
A transmission line has Z0 = 300 Ω and ZL = (300 - j300) ohm. The transmission coefficient is |
| A. | 1.265 ∠ - 18.43° |
| B. | 1.01 ∠ - 10° |
| C. | 1.14 ∠ 66.68° |
| D. | 1.09 ∠ 66.68° |
| Answer» B. 1.01 ‚à† - 10¬∞ | |
| 449. |
Dielectric constant and conductivity of rocky soil and flat sandy soil are around |
| A. | 10 and 20 mho/cm respectively |
| B. | 20 and 10 mho/cm respectively |
| C. | 2 and 5 mho/cm respectively |
| D. | 0.5 and 2 mho/cm respectively |
| Answer» B. 20 and 10 mho/cm respectively | |
| 450. |
Which TM mode in rectangular waveguide has lowest cutoff frequency? |
| A. | TM11 |
| B. | TM01 |
| C. | TM10 |
| D. | TM21 |
| Answer» B. TM01 | |