MCQOPTIONS
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MCQOPTIONS
This section includes 247 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
The key difference between circuit theory and transmission line theory is: |
| A. | circuit elements |
| B. | voltage |
| C. | current |
| D. | electrical size |
| Answer» E. | |
| 102. |
Propagation constant γ is given by: |
| A. | α+jβ |
| B. | α-jβ |
| C. | α/jβ |
| D. | α.jβ |
| Answer» B. α-jβ | |
| 103. |
To get an admittance chart from an impedance chart: |
| A. | smith chart has to be rotated by 90â° |
| B. | smith chart has to be rotated by 180â° |
| C. | admittance chart cannot be obtained from the impedance chart anyway. |
| D. | none of the mentioned |
| Answer» C. admittance chart cannot be obtained from the impedance chart anyway. | |
| 104. |
Smith chart is based on the polar plot of: |
| A. | reactance |
| B. | voltage |
| C. | current |
| D. | voltage reflection co-efficient |
| Answer» E. | |
| 105. |
If a transmission line of characteristic impedance 50 Ω is terminated with a load impedance of 150 Ω , then VSWR is: |
| A. | 0.75 |
| B. | 0.5 |
| C. | 2 |
| D. | none of the mentioned |
| Answer» B. 0.5 | |
| 106. |
Flow of power in transmission line takes place through: |
| A. | electric field and magnetic field |
| B. | voltage and current |
| C. | voltage |
| D. | electric field |
| Answer» B. voltage and current | |
| 107. |
If a transmission line of characteristic impedance 50 Ω is to be matched to a load of 100Ω, then the characteristic impedance of the ƛ/4 transmission line to be used is: |
| A. | 75 Ω |
| B. | 50 Ω |
| C. | 100 Ω |
| D. | 70.71 Ω |
| Answer» E. | |
| 108. |
If a transmission line of a characteristics impedance 50 Ω is terminated with a load impedance of 100 Ω, then the reflection co efficient is: |
| A. | 0.3334 |
| B. | 0.6667 |
| C. | 1.6 |
| D. | 1.333 |
| Answer» B. 0.6667 | |
| 109. |
Voltage reflection coefficient can be defined as: |
| A. | ratio of amplitude of reflected voltage wave to the transmitted voltage wave |
| B. | ratio of amplitude of reflected voltage to the incident voltage wave |
| C. | ratio of load impedance to the characteristic impedance of the transmission line |
| D. | none of the mentioned |
| Answer» C. ratio of load impedance to the characteristic impedance of the transmission line | |
| 110. |
In a MTI radar, the quartz delay line is used to |
| A. | match the phase of coho and output oscillator |
| B. | match the phase of coho and stalo |
| C. | match the signal with echo |
| D. | subtract a complete scan from previous scan |
| Answer» E. | |
| 111. |
Which one of the following device behaviour is governed by bulk effect? |
| A. | impatt diode |
| B. | gunn diode |
| C. | tunnel diode |
| D. | pin diode |
| Answer» C. tunnel diode | |
| 112. |
The solid area through which all the power radiated by the antenna is: |
| A. | beam area |
| B. | effective area |
| C. | aperture area |
| D. | beam efficiency |
| Answer» B. effective area | |
| 113. |
__________ system obtains information about a target by transmitting a signal and receiving the echo from the target. |
| A. | radar |
| B. | sonar |
| C. | radiometer |
| D. | none of the above |
| Answer» B. sonar | |
| 114. |
The radar in which both transmission and reception is done using the same antenna are called: |
| A. | monostatic |
| B. | bistatic |
| C. | dipole radar |
| D. | monopole radar |
| Answer» B. bistatic | |
| 115. |
slotted antenna is used for |
| A. | uhf |
| B. | vhf |
| C. | none of the above |
| D. | both uhf and vhf |
| Answer» E. | |
| 116. |
Micro strip can be fabricated using: |
| A. | photolithographic process |
| B. | electrochemical process |
| C. | mechanical methods |
| D. | none of the above |
| Answer» B. electrochemical process | |
| 117. |
The parabolic and lens antennas are used extensively at |
| A. | sw |
| B. | mw |
| C. | microwaves |
| D. | al of the above |
| Answer» D. al of the above | |
| 118. |
One of the following antenna types is best excited from a waveguide |
| A. | horn antenna |
| B. | helical antenna |
| C. | biconical antenna |
| D. | log periodic antenna |
| Answer» B. helical antenna | |
| 119. |
Lens antennas used for microwaves are usually made of |
| A. | paraboloid surfaces |
| B. | polystyrene |
| C. | dielectric media having large refractive index |
| D. | glass of low refractive index |
| Answer» C. dielectric media having large refractive index | |
| 120. |
The television receiver antennas are usually |
| A. | parabolic dish type |
| B. | helical antennas |
| C. | dipoles |
| D. | none of the above |
| Answer» D. none of the above | |
| 121. |
Parabolic and lens antennas are extensively used for |
| A. | short waves |
| B. | micro waves |
| C. | medium frequency waves |
| D. | all of the above |
| Answer» C. medium frequency waves | |
| 122. |
Power density is basically termed as power per unit are |
| A. | reflected |
| B. | radiated |
| C. | diffracted |
| D. | refracted |
| Answer» C. diffracted | |
| 123. |
A measure of the mismatched between line and load impedance is called as |
| A. | reflection coefficient |
| B. | standing wave ratio |
| C. | loss |
| D. | standing waves |
| Answer» C. loss | |
| 124. |
Reflections on a transmission line can occur when |
| A. | impedance of the source and load are matched |
| B. | impedance of the source and the load are mismatched |
| C. | resonance conditions are obtained |
| D. | power transfer between source and load is maximum |
| Answer» C. resonance conditions are obtained | |
| 125. |
Which of the following is used to measure SWR? |
| A. | multimeter |
| B. | spectrum analyzer |
| C. | reflectometer |
| D. | oscilloscope |
| Answer» D. oscilloscope | |
| 126. |
The load is properly matched with the transmission line if the standing wave ratio is equal to |
| A. | 50 |
| B. | 10 |
| C. | 5 |
| D. | 1 |
| Answer» E. | |
| 127. |
In a transmission line, if the SWR or maximum current to a minimum current ratio of 2:1, the ratio of the maximum voltage to the minimum voltage is |
| A. | 1:4 |
| B. | 4:1 |
| C. | 1:2 |
| D. | 2:1 |
| Answer» E. | |
| 128. |
Considering a coaxial transmission line, maximum voltage on the line divided by the minimum voltage equals the |
| A. | characteristic impedance |
| B. | iswr |
| C. | vswr |
| D. | inductive reactance |
| Answer» D. inductive reactance | |
| 129. |
For best low-level noise performance in the X-band, an amplifier should use |
| A. | a bipolar transistor |
| B. | a gunn diode |
| C. | a step-recovery diode |
| D. | an impatt diode |
| Answer» D. an impatt diode | |
| 130. |
A disadvantage of microstrip compared with strip line is that micro strip |
| A. | does not readily lend itself to printed circuit techniques |
| B. | is more likely to radiate |
| C. | is bulkier |
| D. | is more expensive and complex to manufacture |
| Answer» B. is more likely to radiate | |
| 131. |
A magnetron whose oscillating frequency is electronically adjustable over a wide range is called a |
| A. | coaxial magnetron |
| B. | dither-tuned magnetron |
| C. | frequency agile magnetron |
| D. | vtm |
| Answer» E. | |
| 132. |
The TWT is sometimes preferred to the magnetron as a radar transmitter output tube because it is |
| A. | capable of a longer duty cycle |
| B. | a more efficient bandwidth |
| C. | more broadband |
| D. | less noisy |
| Answer» B. a more efficient bandwidth | |
| 133. |
The primary purpose of the helix in a traveling-wave tube is to |
| A. | prevent the electron beam from spreading in the long tube |
| B. | reduce the axial velocity of the rf field |
| C. | ensure broadband operationreduce the noise figure |
| D. | none ofthe above. |
| Answer» C. ensure broadband operationreduce the noise figure | |
| 134. |
The cavity magnetron uses strapping to |
| A. | prevent mode jumping |
| B. | prevent cathode back heating |
| C. | ensure bunching |
| D. | improve the phase focusing effect |
| Answer» B. prevent cathode back heating | |
| 135. |
The multicavity klystron |
| A. | is not a good low-level amplifier because of noise |
| B. | has a higher repeller voltage to ensure a rapid transit time |
| C. | is not suitable for pulsed operation |
| D. | needs a long transit time through the buncher cavity to ensure current modulation |
| Answer» B. has a higher repeller voltage to ensure a rapid transit time | |
| 136. |
Indicate the false statement. Transit time in microwave tubes will be reduced if |
| A. | the electrodes are brought closer together |
| B. | a higher anode current is used |
| C. | multiple or coaxial leads are used |
| D. | the anode voltage is made larger |
| Answer» D. the anode voltage is made larger | |
| 137. |
A microwave tube amplifier uses an axial magnetic field and a radial electric field. This is the |
| A. | reflex klystron |
| B. | coaxial magnetron |
| C. | travelling wave magnetron |
| D. | cfa |
| Answer» C. travelling wave magnetron | |
| 138. |
A PIN diode is |
| A. | a metal semiconductor point-contact diode |
| B. | a microwave mixer diode |
| C. | suitable for use as a microwave switch |
| D. | often used as a microwave detector |
| Answer» D. often used as a microwave detector | |
| 139. |
A ferrite is |
| A. | a nonconductive with magnetic properties |
| B. | an intermetallic compound with particularly good conductivity |
| C. | an insulator which heavily attenuates magnetic fields |
| D. | a microwave semiconductor invented by faraday |
| Answer» B. an intermetallic compound with particularly good conductivity | |
| 140. |
A directional coupler with three or more holes is sometimes used in preference to the two-hole couple |
| A. | because it is more efficient |
| B. | to increase coupling of signal |
| C. | to reduce spurious mode generation |
| D. | to increase the bandwidth of the system |
| Answer» D. to increase the bandwidth of the system | |
| 141. |
Which of the following waveguides tuning components is not easily adjustable? |
| A. | screw |
| B. | stub |
| C. | iris |
| D. | plunger |
| Answer» D. plunger | |
| 142. |
When an electromagnetic waves are propagated in a waveguide |
| A. | they travel along a broader walls of the guide |
| B. | they are reflected from the walls but do not travel along them |
| C. | they travel through the dielectric without touching the walls |
| D. | they travel along all four walls of the waveguide |
| Answer» C. they travel through the dielectric without touching the walls | |
| 143. |
ency of 30 GHz is (free space impedance 0 =377 Ω) |
| A. | 308 Ω |
| B. | 400 Ω |
| C. | 355 Ω |
| D. | 461 Ω |
| Answer» C. 355 Ω | |
| 144. |
ency for the dominant mode is |
| A. | 2.5 ghz |
| B. | 10 ghz |
| C. | 5 ghz |
| D. | 12.5 ghz |
| Answer» B. 10 ghz | |
| 145. |
The cut off frequency of waveguide depends upon |
| A. | the dimensions of the waveguide. |
| B. | the dielectric property of the medium in the waveguide. |
| C. | the characteristic impedance of the waveguide |
| D. | the transverse and axial components of the fields |
| Answer» B. the dielectric property of the medium in the waveguide. | |
| 146. |
. Consider an air filled rectangular waveguide with a cross – section of5 cm × 3 cm. For this waveguide, the cut off frequency (in MHz) of TE21mode is |
| A. | 7.81 ghz |
| B. | 9.01 ghz |
| C. | 11.2 ghz |
| D. | 6.89 ghz |
| Answer» B. 9.01 ghz | |
| 147. |
The phase velocity of an electrometric wave propagating in a hollow metallic rectangular waveguide in the TE10 mode is |
| A. | equal to its group velocity |
| B. | less than velocity of light in free space |
| C. | equal to velocity of light in free space |
| D. | greater than velocity of light in free space |
| Answer» D. greater than velocity of light in free space | |
| 148. |
The phase velocity for the TE10 mode in an air filled rectangular waveguide is |
| A. | less than c |
| B. | greater than c |
| C. | equal to c |
| D. | none of the above |
| Answer» D. none of the above | |
| 149. |
The dominant mode in a rectangular waveguide is TE10 because this mode has |
| A. | no attenuation |
| B. | no cut off |
| C. | no magnetic field component |
| D. | the highest cut off wavelength |
| Answer» E. | |
| 150. |
Indicate which one of the following modes do not exist in a rectangularresonant cavity |
| A. | te110 |
| B. | tm110 |
| C. | te011 |
| D. | mt111 |
| Answer» B. tm110 | |