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.
| 501. |
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. | |
| 502. |
Skin effect is more pronounced at high frequencies. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 503. |
In a magnetron the magnetic flux density is of the order of |
| A. | 1 mWb/s |
| B. | 1 Wb/m2 |
| C. | 106 m/s |
| D. | 1012 m/s |
| Answer» B. 1 Wb/m2 | |
| 504. |
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 | |
| 505. |
A circular polarizer converts a linearly polarized wave into a circularly polarised wave. |
| A. | 1 |
| B. | |
| C. | 1.706 D |
| D. | 2.11 D |
| Answer» B. | |
| 506. |
Consider the following statements (L is the length of array between centres of end antennas and A is wave-length)Width of major lobe between nulls of broad side array and end fire array are different.Directive gain of broadside array and end fire array are different.Directive gain of broadside array is 4 Which of the above statements are correct? |
| A. | 1, 2 and 3 |
| B. | 1 and 2 only |
| C. | 1 only |
| D. | 1 and 3 only |
| Answer» E. | |
| 507. |
Consider the following statements Impedance of Gunn diode is about tens of ohms.Impedance of Impatt diode is a few ohms.Impedance of Impatt diode are of the same order.Impedance of Impatt diode is more than that of Gunn diode. Which of the above statement are correct? |
| A. | all |
| B. | 1 and 2 only |
| C. | 1, 2 and 3 |
| D. | 1, 2 and 4 |
| Answer» C. 1, 2 and 3 | |
| 508. |
The bunching action which occurs in multicavity klystron amplifier can be represented by Applegate diagram |
| A. | 1 |
| B. | |
| Answer» B. | |
| 509. |
Consider the following statements about hybrid ring Ports 1 and 2 are decoupled.Port 3 and 4 are coupled.A signal entering either port 1 or 2 splits equally between ports 3 and 4.A signal entering either port 3 or 4 splits equally between ports 1 and 2. Which of the above are correct? |
| A. | 1, 2, 3 and 4 |
| B. | 1, 3 and 4 |
| C. | 1 and 2 |
| D. | 2, 3 and 4 |
| Answer» C. 1 and 2 | |
| 510. |
In an optional fiber the refractive index of cladding material should be |
| A. | nearly 1 |
| B. | very low |
| C. | less than that of core |
| D. | more than that of core |
| Answer» D. more than that of core | |
| 511. |
The reverse voltage applied to a varactor diode |
| A. | is less than avalanche breakdown voltage |
| B. | is more than avalanche breakdown voltage |
| C. | may be more or less than a avalanche breakdown voltage |
| D. | is very high as compared to avalanche breakdown voltage |
| Answer» B. is more than avalanche breakdown voltage | |
| 512. |
A short circuited stub is preferred to an open circuited stub because an open circuited stub |
| A. | is more difficult to fabricate and construct |
| B. | is made of transmission line of different Z0 |
| C. | is liable to radiate |
| D. | is incapable of giving full range of reactance |
| Answer» D. is incapable of giving full range of reactance | |
| 513. |
For a circular wave guide |
| A. | cutoff frequency for TE10 and TE01 modes are same |
| B. | cutoff frequency for TE10 and TE01 modes are different |
| C. | cutoff frequency for TE10 mode = twice the cutoff frequency for TE20 mode |
| D. | cutoff frequency for TE10 mode = haf the cutoff frequency for TE20 mode |
| Answer» B. cutoff frequency for TE10 and TE01 modes are different | |
| 514. |
Assertion (A): Two equal and opposite travelling waves result in a standing wave.Reason (R): The ratio of maximum to minimum value of a standing wave is called SWR. |
| 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 | |
| 515. |
The p mode of operation of magnetron signifies that |
| A. | the phase difference between adjacent anode poles is p radians |
| B. | the phase difference between adjacent anode poles is a multiple of p radians |
| C. | the total phase shift around the periphery is p radians |
| D. | none of the above |
| Answer» B. the phase difference between adjacent anode poles is a multiple of p radians | |
| 516. |
What is the numerical aperture an optical fiber when critical angle is 30°? |
| A. | 0.5 |
| B. | 0.704 |
| C. | 0.866 |
| D. | 0.2 |
| Answer» B. 0.704 | |
| 517. |
In a circular waveguide TE21 mode has lowest cutoff frequency |
| A. | 1 |
| B. | |
| C. | 5 |
| D. | 10 |
| Answer» C. 5 | |
| 518. |
The diagram to show distance time history of electrons in klystron amplifier is called |
| A. | apple gate diagram |
| B. | asynchronous diagram |
| C. | bunching diagram |
| D. | velocity modulation diagram |
| Answer» B. asynchronous diagram | |
| 519. |
Reflex klystron oscillator is essentially a low power device |
| A. | 1 |
| B. | |
| Answer» B. | |
| 520. |
In a microstrip transmission the signal can be easily redirected by changing the centre strip. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 521. |
Assertion (A): Gunn diode is a transferred electron device.Reason (R): A Gunn oscillator uses the phenomenon of 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 | |
| 522. |
Which of the following is a balanced line? |
| A. | Coaxial line |
| B. | Strip line |
| C. | Microstrip line |
| D. | TV twin lead |
| Answer» E. | |
| 523. |
Assertion (A): Inter-digitated geometry is widely used for microwave transistors.Reason (R): Tuning at input and output of transistor uses MOS chip capacitors. |
| 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 | |
| 524. |
Both Impatt and Trapatt devices use avalanche effect |
| A. | 1 |
| B. | |
| Answer» B. | |
| 525. |
Which one of the following is not a negative resistance device? |
| A. | Gunn diode |
| B. | Tunnel diode |
| C. | Impatt diode |
| D. | Varactor diode |
| Answer» E. | |
| 526. |
A 75 ohm line is first short terminated and minima locations are noted. Then the short is replaced by resistive load and minima location are again noted. If minima location are not altered and VSWR is 3, the value of resistive load is |
| A. | 25 Ω |
| B. | 50 Ω |
| C. | 225 Ω |
| D. | 250 Ω |
| Answer» D. 250 Œ© | |
| 527. |
A 10 km long line has a characteristic impedance of 400 ohms. If line length is 100 km, the characteristic impedance is |
| A. | 4000 Ω |
| B. | 400 Ω |
| C. | 40 Ω |
| D. | 4 Ω |
| Answer» C. 40 Œ© | |
| 528. |
In a reflex klystron the output frequency is determined primarily by resonant frequency of cavity. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 529. |
The use of coaxial microwave line should be restricted to frequencies |
| A. | below cut off frequency of TE11 mode |
| B. | above cut off frequency of TE11 mode |
| C. | at frequencies much lower than cut off frequency of TE11 mode |
| D. | at frequencies much higher than cut off frequency of TE11 mode |
| Answer» B. above cut off frequency of TE11 mode | |
| 530. |
A waveguide connected to a circularly polarized antenna must be able to efficiently propagate both vertically and horizontally polarised waves. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 531. |
Klystron amplifier is not used to amplifier very weak microwave signals due to |
| A. | low gain for weak signals |
| B. | low noise for weak signals |
| C. | high noise |
| D. | both (a) and (b) |
| Answer» D. both (a) and (b) | |
| 532. |
The reflection coefficient on a line is 0.2 ∠45°. The SWR is |
| A. | 0.8 |
| B. | 1.1 |
| C. | 1.2 |
| D. | 1.5 |
| Answer» E. | |
| 533. |
The directivity in a receiving antenna increases the intercept area in forward directionreduces the noise picked up from other sourcesprovides a means of discriminating against undesired signals originating in directions other than in which the desired transmitter lies. Which of the above statements are correct? |
| A. | 1 only |
| B. | 1 and 2 only |
| C. | 1, 2 and 3 |
| D. | 2 and 3 only |
| Answer» D. 2 and 3 only | |
| 534. |
In the given figure the time taken by the wave to make one round trip is |
| A. | 10 ns |
| B. | 20 ns |
| C. | 30 ns |
| D. | 40 ns |
| Answer» E. | |
| 535. |
Microwave resonators are used in |
| A. | microwave oscillators |
| B. | microwave narrow band amplifier |
| C. | microwave frequency metres |
| D. | all of the above |
| Answer» E. | |
| 536. |
In 8 cavity magnetron the p mode corresponds to a total phase shift equal to |
| A. | ± 8 p radians around the periphery |
| B. | ± 4 p radians around the periphery |
| C. | ± 2 p radians around the periphery |
| D. | ± 16 p radians around the periphery |
| Answer» B. ¬± 4 p radians around the periphery | |
| 537. |
A line has Z0 = 300 ∠ 0° Ω. If ZL = 150 ∠ 0° Ω, reflection coefficient is |
| A. | 0.5 |
| B. | 0.3333 |
| C. | -0.3333 |
| D. | -0.5 |
| Answer» D. -0.5 | |
| 538. |
A loss less line of characteristic impedance Z0 is terminated in pure reactance of -jZ0 value. VSWR is |
| A. | 10 |
| B. | 2 |
| C. | 1 |
| D. | infinity |
| Answer» E. | |
| 539. |
In a klystron amplifier the input cavity is called |
| A. | buncher |
| B. | catcher |
| C. | Pierce gun |
| D. | collector |
| Answer» B. catcher | |
| 540. |
Which of the following parameters is negligible in transmission lines? |
| A. | R |
| B. | L |
| C. | C |
| D. | G |
| Answer» E. | |
| 541. |
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 | |
| 542. |
A cavity resonator is |
| A. | a hollow metallic enclosure |
| B. | a hollow enclosure having magnetic material as its walls |
| C. | a hollow enclosure having dielectric material as its walls |
| D. | either (b) or (c) |
| Answer» B. a hollow enclosure having magnetic material as its walls | |
| 543. |
The domain mode in rectangular waveguide is |
| A. | TE01 |
| B. | TE02 |
| C. | TE10 |
| D. | TM11 |
| Answer» D. TM11 | |
| 544. |
Which of the following lines is non-radiating? |
| A. | Open two wire |
| B. | Coaxial |
| C. | Both |
| D. | None of the above |
| Answer» C. Both | |
| 545. |
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 | |
| 546. |
Which one of the following is also called 'rat race'? |
| A. | E plane tee |
| B. | H plane tee |
| C. | Magic tee |
| D. | Hybrid ring |
| Answer» E. | |
| 547. |
In a circular waveguide the dominant mode is |
| A. | TE01 |
| B. | TE11 |
| C. | TE20 |
| D. | TE21 |
| Answer» C. TE20 | |
| 548. |
A resistive microwave load with ZL = 150 Ω is connected to 50 Ω 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) | |
| 549. |
Consider the following statements, SWR of a transmission line is infinite when the load is a short circuita complex impedancean open circuita pure reactance Which of the above statements are correct? |
| A. | 1 and 3 only |
| B. | 1, 2, 3 |
| C. | 2, 3, 4 |
| D. | 1, 2, 4 |
| Answer» B. 1, 2, 3 | |
| 550. |
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 | |