MCQOPTIONS
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MCQOPTIONS
This section includes 51 Mcqs, each offering curated multiple-choice questions to sharpen your Electromagnetic Theory knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Consider the following statements:1. Additional cavities serve to velocity-modulate the electron beam and produce an increase in the energy available at the output.2. The addition of intermediate cavities between the input and output cavities of the basic klystron greatly improves the amplification, power output, and efficiency of the klystron.Which of the above statements is/are correct? |
| A. | 1 only |
| B. | 2 only |
| C. | Both 1 and 2 |
| D. | Neither 1 nor 2 |
| Answer» D. Neither 1 nor 2 | |
| 2. |
In a two cavity klystron, the input cavity resonator is also known as |
| A. | Velocity modulator |
| B. | Catcher cavity |
| C. | Buncher cavity |
| D. | Accelerator |
| Answer» D. Accelerator | |
| 3. |
Direction: Question consists of two statements, one labelled as the 'Assertion (A)' and the other as 'Reason (R)'. Examine these two statements carefully and select the answer to this question using the codes given below:Assertion (A): TEM (Transfer Electro-Magnetic) waves cannot propagate within a hollow waveguide of any shape.Reason (R): For a TEM wave to exist within the waveguide, lines of the H field must be closed loops that require an axial component of E which is not present in a TEM wave. |
| A. | Both A and R are individually true and R is the correct explanation of A |
| B. | Both A and R are individually true but R is not the correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» C. A is true but R is false | |
| 4. |
An X - band pulse cylindrical magnetron has the following parameters:Anode voltage = 26 kV, Beam current = 27 A, Magnetic flux density = 0.336 Wb/m2, Radius of Cathode Cylinder = 5 cm, Radius of Vane edge to center = 10 cm.The following data regarding angular frequency and Cut off voltage is given.(a) Angular frequency = 5.91 × 1010 rad(b) Cut off voltage = 139.50 kV(c) angular frequency = 3.91 × 109 radian(d) Cut off voltage = 239.39 kVWhich is the correct option? |
| A. | (a) and (b) |
| B. | (b) and (c) |
| C. | (c) and (d) |
| D. | (d) and (a) |
| Answer» B. (b) and (c) | |
| 5. |
A waveguide section in microwave circuits will act as a: |
| A. | Low-pass filter |
| B. | Band-pass filter |
| C. | Band-stop filter |
| D. | High-pass filter |
| Answer» E. | |
| 6. |
Magnetron is a:a) O - type tubeb) a low power devicec) a high power deviced) an oscillatorOut of the above following is the correct option: |
| A. | (a) and (b) |
| B. | (b) and (d) |
| C. | (c) and (d) |
| D. | (a), (c) and (d) |
| Answer» D. (a), (c) and (d) | |
| 7. |
Characteristics impedance of a waveguide with cross sectional dimensions 5 cm and 4 cm and cut-off frequency to frequency of operation ratio equal to 0.6, assuming dielectric constant to be 9 is |
| A. | 157 Ω |
| B. | 400 Ω |
| C. | 75 Ω |
| D. | 45 Ω |
| Answer» B. 400 Ω | |
| 8. |
Match the two lists and choose the correct answer from the code given below:List IList II(a) TE mode(i) No magnetic field in the direction of preparation(b)TM mode(ii) No electric, no magnetic field in the direction of propagation(c) TEM mode(iii) Both electric and magnetic field present in the direction of propagation(d) Hybrid mode(iv) No electric field in the direction of propagation |
| A. | (a) – (iv), (b) – (iii), (c) – (i), (d) – (ii) |
| B. | (a) – (iv), (b) – (ii), (c) – (i), (d) – (iii) |
| C. | (a) – (iv), (b) – (i), (c) – (ii), (d) – (iii) |
| D. | (a) – (i), (b) – (iv), (c) – (ii), (d) – (iii) |
| Answer» D. (a) – (i), (b) – (iv), (c) – (ii), (d) – (iii) | |
| 9. |
If the maximum electron density for E layer in ionosphere is 9 × 106 electrons/cm3, then its critical frequency is |
| A. | 81 MHz |
| B. | 9 MHz |
| C. | 27 MHz |
| D. | 54 MHz |
| Answer» D. 54 MHz | |
| 10. |
An air-filled rectangular waveguide has dimensions of a = 6 cm and b = 4 cm. The signal frequency is 3 GHz. Match List 1 with List 2 and select the correct answer using the code given below the lists:List 1List 2 1. TE10 A. 2.5 GHz 2. TE01 B. 3.75 GHz 3. TE11 C. 4.506 GHz 4. TM11 D. 4.506 GHz |
| A. | 1 - A, 2 - B, 3 - C, 4 - D |
| B. | 1 - D, 2 - B, 3 - C, 4 - A |
| C. | 1 - A, 2 - C, 3 - B, 4 - D |
| D. | 1 - D, 2 - C, 3 - B, 4 - A |
| Answer» B. 1 - D, 2 - B, 3 - C, 4 - A | |
| 11. |
Direction: Given question consists of two statements, one labeled as the 'Assertion (A)' and the other as 'Reason (R)'. You are to examine these two statements carefully and select the answers to these items using the codes given below.Assertion (A): A unique property of TMon modes in circular waveguides is a rapid decrease in attenuation with increasing frequency.Reason (R): The circular waveguides find application in long low-loss communication. |
| A. | Both A and R are individually true and R is the correct explanation of A |
| B. | Both A and R are individually true but R is NOT the correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» E. | |
| 12. |
\(n = \sqrt{(\frac{m\pi}{a})^2 + (\frac{n\pi}{b})^2 - \omega^2 \mu \epsilon}\) represents the propagation constant in a rectangular waveguide for: |
| A. | TE waves only |
| B. | TM waves only |
| C. | TEM waves |
| D. | TE and TM waves only. |
| Answer» E. | |
| 13. |
For a dominant mode in a rectangular waveguide with breadth 10 cm, the guide wavelength for a signal of 2.5 GHz will be |
| A. | 20 cm |
| B. | 18 cm |
| C. | 15 cm |
| D. | 12 cm |
| Answer» D. 12 cm | |
| 14. |
A 20 dB directional coupler is shown in the figure:The power output at port 3 will be |
| A. | 10 mW |
| B. | 1 mW |
| C. | 5 mW |
| D. | 2 mW |
| Answer» C. 5 mW | |
| 15. |
In TEm, n mode, m, and n are integers denoting the number of |
| A. | 1/2 the wavelengths of intensity between each pair of walls |
| B. | 1/3 the wavelengths of intensity between each pair of walls |
| C. | 1/4 the wavelengths of intensity between each pair of walls |
| D. | 1/8 the wavelengths of intensity between each pair of walls |
| Answer» B. 1/3 the wavelengths of intensity between each pair of walls | |
| 16. |
For a WR 90 waveguide, the cut-off frequency for TE20 mode is 16 GHz. Then the cut-off frequency for TE11 mode will be: |
| A. | 4√3 GHz |
| B. | 6√3 GHz |
| C. | 8√5 GHz |
| D. | 16√5 GHz |
| Answer» D. 16√5 GHz | |
| 17. |
In two wire transmission line, two consecutive voltage minima are found at 20.6 cm and 25.6 cm. The operating frequency |
| A. | 3.5 GHz |
| B. | 3 GHz |
| C. | 1 GHz |
| D. | 2.5 GHz |
| Answer» C. 1 GHz | |
| 18. |
Microwave link repeaters are typically 50 Km apart because of |
| A. | Atmospheric attenuation |
| B. | Earth’s curvature |
| C. | Output tube power limitation |
| D. | Both a & b |
| Answer» C. Output tube power limitation | |
| 19. |
In cylindrical waveguides the attenuation will be minimum, at a frequency which is √3 times the cutoff frequency for the following modes of operations1. TE102. TM113. TM104. TE11Which of the above are correct ? |
| A. | 1, 2, 3 and 4 |
| B. | 2 and 3 only |
| C. | 1 and 2 only |
| D. | 3 and 4 only |
| Answer» E. | |
| 20. |
Klystron operation is based on the principle of |
| A. | Velocity modulation |
| B. | Amplitude modulation |
| C. | Frequency modulation |
| D. | Phase modulation |
| Answer» B. Amplitude modulation | |
| 21. |
For a wave propagating inside a rectangular waveguide structure, the wave impedance for TE is always ______ TM mode of propagation. |
| A. | Less than |
| B. | Greater than |
| C. | Depends on operating frequency |
| D. | Equal to |
| Answer» C. Depends on operating frequency | |
| 22. |
Consider the following statementsFor a rectangular waveguide with dimensions a × b where b is the narrow dimension, small value of b1. Gives a larger separation between cutoff frequencies of TE01 and TE10 modes.2. Gives increased attenuation.3. Limits power handling capabilities because of breakdown field limits.Which of the above statement is/are correct ? |
| A. | 1 and 2 only |
| B. | 1, 2 and 3 |
| C. | 2 only |
| D. | 3 only |
| Answer» C. 2 only | |
| 23. |
Consider the following statements:Plane-wave propagation through circular waveguide results in1. TE modes2. TM modesWhich of the above statements is /are correct? |
| A. | 1 only |
| B. | 2 only |
| C. | Either 1 or 2 |
| D. | Both 1 and 2 |
| Answer» D. Both 1 and 2 | |
| 24. |
For the dominant mode of operation in an air-filled circular waveguide of an inner diameter of 4 cm, determine the cut-off frequency? |
| A. | 4.395 GHz |
| B. | 2.196 GHz |
| C. | 8.674 GHz |
| D. | 1.148 GHz |
| Answer» B. 2.196 GHz | |
| 25. |
During wave propagation in an air-filled rectangular waveguide:1) Wave impedance is never less than the free-space impedance2) Propagation constant is an imaginary number3) TEM mode is possible if the dimensions of the waveguide are properly chosenWhich of the above are correct? |
| A. | 1 and 2 only |
| B. | 1 and 3 only |
| C. | 2 and 3 only |
| D. | 1, 2, and 3 |
| Answer» B. 1 and 3 only | |
| 26. |
In a microwave system, waveguides have the advantages of |
| A. | High power-handling capability and low loss |
| B. | Thin dielectric substrate |
| C. | Low power-handling and adequate stability |
| D. | Positive phase shift |
| Answer» B. Thin dielectric substrate | |
| 27. |
A dead-ended waveguide serving as a resonant element in a microwave circuit is called as: |
| A. | Cavity resonator |
| B. | physical barrier |
| C. | Antenna |
| D. | Pringles |
| Answer» B. physical barrier | |
| 28. |
Direction: Question consists of two statements, one labelled as the 'Assertion (A)' and the other as 'Reason (R)'. Examine these two statements carefully and select the answer to this question using the codes given below:Assertion (A): To obtain high Q, a resonator should have a large ratio of volume to surface area.Reason (R): It is the volume that stores energy and it is the surface area that dissipates energy. |
| A. | Both A and R are individually true and R is the correct explanation of A |
| B. | Both A and R are individually true but R is not the correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are individually true but R is not the correct explanation of A | |
| 29. |
Consider the following statements relating to the cavity resonator1. The cavity resonator does not possess as many modes as the corresponding waveguide does.2. The resonant frequencies of cavities are very closely spaced.3. The resonant frequency of a cavity resonator can be changed by altering its dimensions.Which of the above statements is/are correct ? |
| A. | 2 and 3 only |
| B. | 2 only |
| C. | 3 only |
| D. | 1, 2 and 3 |
| Answer» B. 2 only | |
| 30. |
For a rectangular waveguide with dimensions 4.8 cm × 2.8 cm, the cut-off frequency for TE22 mode is: |
| A. | 12.4 GHz |
| B. | 24.8 GHz |
| C. | 6.2 GHz |
| D. | 8.5 GHz |
| Answer» B. 24.8 GHz | |
| 31. |
For a standard rectangular waveguide having an aspect ratio of 2 : 1, the cutoff wavelength for TM1,1 mode will be nearly |
| A. | 0.9a |
| B. | 0.7a |
| C. | 0.5a |
| D. | 0.3a |
| Answer» B. 0.7a | |
| 32. |
Pollen count and Solar Protons affects the Microwave Link by |
| A. | Increasing the gain of the receiver |
| B. | Increase in the Interference |
| C. | Increasing the Distance Covered |
| D. | None of these |
| Answer» C. Increasing the Distance Covered | |
| 33. |
In a waveguide with perfectly conducting flat wall, the angle of reflection is equal to the angle of |
| A. | Diffraction |
| B. | Incidence |
| C. | Refraction |
| D. | Penetration |
| Answer» C. Refraction | |
| 34. |
Find the cutoff frequency of dominant mode in an air-filled circular waveguide having inner radius of 1 cm which is excited in dominant mode at 12 GHz. |
| A. | 10 GHz |
| B. | 3.5 GHz |
| C. | 6.5 GHz |
| D. | 8.791 GHz |
| Answer» E. | |
| 35. |
A rectangular waveguide is 5.1 cm by 2.4 cm (inside measurements). The cut off frequency of the dominant mode will be nearly |
| A. | 5.38 GHz |
| B. | 4.54 GHz |
| C. | 3.78 GHz |
| D. | 2.94 GHz |
| Answer» E. | |
| 36. |
Impedance inversion may be obtained with __________ |
| A. | a short-circuited stub |
| B. | an open circuited stub |
| C. | a quarter wave line |
| D. | a half wave line |
| Answer» D. a half wave line | |
| 37. |
A dominant mode of a waveguide is characterized by lowest:1. Cut-off frequency2. Cut-off wavelength3. Attenuation |
| A. | 1 only |
| B. | 1 and 3 only |
| C. | 2 and 3 only |
| D. | 1, 2 and 3 |
| Answer» B. 1 and 3 only | |
| 38. |
A Travelling Wave Tube Amplifier (TWTA) has the following properties:a) It provides an octave Bandwidthb) It provides an approximate gain of 40 dB and morec) It has a low noise figured) It has a very high noise figureOut of the above statements following is correct: |
| A. | (a), (b) and (d) only |
| B. | (a) and (d) only |
| C. | (a) and (b) only |
| D. | (a) and (b) and (c) only |
| Answer» E. | |
| 39. |
Microwaves propagates through waveguide in |
| A. | Straight Path |
| B. | Circular Path |
| C. | Zigzag path due to reflection of guide |
| D. | Analog the outer surface of the waveguide |
| Answer» D. Analog the outer surface of the waveguide | |
| 40. |
In a microwave measurement setup, the power reaching to the load is found to be 50 mW. If a 3 dB coupler is placed before the load, the power to the load will be |
| A. | 50 mW |
| B. | 25 mW |
| C. | 12.5 mW |
| D. | 6.25 mW |
| Answer» C. 12.5 mW | |
| 41. |
Cut off wavelength of a rectangular waveguide for TE10, if 'a' is the width and 'b' is the height (a > b) |
| A. | 2a |
| B. | 2b |
| C. | a |
| D. | b |
| Answer» B. 2b | |
| 42. |
A 10 GHz signal is propagated in a waveguide whose wall separation is 6 cm. The greatest number of half-waves of electric intensity will be possible to establish between the two walls. The guide wavelength for this mode of propagation will be |
| A. | 6.48 cm |
| B. | 4.54 cm |
| C. | 2.48 cm |
| D. | 1.54 cm |
| Answer» C. 2.48 cm | |
| 43. |
Cassegrain feed is used with a parabolic reflector to: |
| A. | increase the gain of the system |
| B. | increase the bandwidth of the system |
| C. | reduce the size of the main reflector |
| D. | allow the feed to be placed at a convenient point |
| Answer» E. | |
| 44. |
Match List-I with List-II and select the correct answer using the code given below the lists:List-IList-II a. Rectangular waveguide i. Plane of polarization b. Waveguide twists ii. Waveguide tuner c. Slotted section iii. TE10 mode d. Stub screws iv. VSWR measurements |
| A. | a - ii, b - iv, c - i, d - iii |
| B. | a - iii, b - iv, c - i, d - ii |
| C. | a - ii, b - i, c - iv, d - iii |
| D. | a - iii, b - i, c - iv, d - ii |
| Answer» E. | |
| 45. |
In a plane travelling wavea) electric and magnetic energy densities are equalb) electric energy density is more than magnetic energy densityc) magnetic energy density is zerod) electric energy density is less than magnetic energy densityChoose the correct answer: |
| A. | is correct but b) is wrong |
| B. | is correct but c) is wrong |
| C. | Both a) and b) are correct |
| D. | Both c) and d) are correct |
| Answer» B. is correct but c) is wrong | |
| 46. |
A lossless air dielectric cylindrical waveguide of inside diameter 2 cm is operated at 10 GHz. For TM 11 mode propagating in +z direction, the following has been evaluated:(i) Cut-off frequency = 9.148 GHz(ii) Cut-off frequency = 8.814 GHz(iii) Wave Impedance = 152.269 Ω (iv) Wave Impedance = 15.26 Ω Which of the above statements are correct?Choose the correct answer from the code given below: |
| A. | (i) and (iii) are correct |
| B. | (ii) and (iii) are correct |
| C. | (ii) and (iv) are correct |
| D. | (i) and (iv) are correct |
| Answer» E. | |
| 47. |
A 250 MHz electromagnetic wave is propagating through a perfect non-magnetic dielectric with ϵr = 6. Its wavelength will be equal to |
| A. | 0.245 m |
| B. | 0.490 m |
| C. | 49 m |
| D. | 4.9 m |
| Answer» C. 49 m | |
| 48. |
An electromagnetic plane wave propagates in a dielectric medium characterised by ϵr = 4 and μr = 1. The phase velocity of the wave will be |
| A. | 0.75 × 108 m/s |
| B. | 1.5 × 108 m/s |
| C. | 3 × 108 m/s |
| D. | 6 × 108 m/s |
| Answer» C. 3 × 108 m/s | |
| 49. |
Directions: The following items consist of two statements, one labeled as “Assertion(A)” and the other labeled as “Reason(R)”. You are to examine the two statements carefully and decide if the Assertion(A) and the Reason(R) are individually true and if so whether the reason is a correct explanation of the assertion. Select your answer to these items using the codes given below and mark your answer accordingly.Assertion (A): A reflex Klystron is a single cavity Klystron that overcomes the disadvantages of two cavity Klystron oscillator.Reason (R): It is a high power microwave generator operating beyond 60 GHz and generating powers in kWs. Its efficiency is very high in the order of 70%. |
| A. | Both (A) and (R) are true and (R) is the correct explanation of (A) |
| B. | Both (A) and (R) are true, but (R) is not the correct explanation of (A) |
| C. | (A) is true, but (R) is false |
| D. | (A) is false, but (R) is true |
| Answer» D. (A) is false, but (R) is true | |
| 50. |
A TE11 mode is propagating through a circular waveguide of radius 5 cm. The dielectric in the waveguide is air. For this following are the data given:(a) Cut off wave number = 38.62(b) Cut off frequency = 1.758 GHz(c) Cut off wave number = 36.82(d) Cut off frequency = 2.758 GHzOut of these following are correct: |
| A. | (a) and (b) |
| B. | (b) and (c) |
| C. | (c) and (d) |
| D. | (a) and (d) |
| Answer» C. (c) and (d) | |