MCQOPTIONS
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MCQOPTIONS
This section includes 217 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. |
Klystron amplifiers have high noise output as compared to crossed field amplifiers. |
| A. | true |
| B. | false |
| Answer» C. | |
| 102. |
Magnetrons are microwave devices that offer very high efficiencies of about 80%. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 103. |
In a                    oscillator, the RF wave travels along the helix from the collector towards the electron gun. |
| A. | interaction oscillator |
| B. | backward wave oscillator |
| C. | magnetrons |
| D. | none o the mentioned |
| Answer» C. magnetrons | |
| 104. |
In crossed field tubes, the electron beam traverses the length of the tube and is parallel to the electric field. |
| A. | true |
| B. | false |
| Answer» C. | |
| 105. |
Microwave tubes are power sources themselves at higher frequencies and can be used independently without any other devices. |
| A. | true |
| B. | false |
| Answer» C. | |
| 106. |
The klystron tube used in a klystron amplifier is a                    type beam amplifier. |
| A. | linear beam |
| B. | crossed field |
| C. | parallel field |
| D. | none of the mentioned |
| Answer» B. crossed field | |
| 107. |
                 is a single cavity klystron tube that operates as on oscillator by using a reflector electrode after the cavity. |
| A. | backward wave oscillator |
| B. | reflex klystron |
| C. | travelling wave tube |
| D. | magnetrons |
| Answer» C. travelling wave tube | |
| 108. |
The production of power at higher frequencies is much simpler than production of power at low frequencies. |
| A. | true |
| B. | false |
| Answer» C. | |
| 109. |
If the RMS peak current in an IMPATT diode is 700 mA and if DC input power is 6 watt, with the load resistance being equal to |
| A. | 10.1 % |
| B. | 10.21 % |
| C. | 12 % |
| D. | 15.2 % |
| Answer» C. 12 % | |
| 110. |
If the critical field in a Gunn diode oscillator is 3.2 KV/cm and effective length is 20 microns, then the critical voltage is: |
| A. | 3.2 v |
| B. | 6.4 v |
| C. | 2.4 v |
| D. | 6.5 v |
| Answer» C. 2.4 v | |
| 111. |
An essential requirement for the BARITT diode is that the intermediate drift region be completely filled to cause the punch through to occur. |
| A. | true |
| B. | false |
| Answer» C. | |
| 112. |
IMPATT diodes employ impact ionization technique which is a noisy mechanism of generating charge carriers. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 113. |
If the length of the intrinsic region in IMPATT diode is 2 µm and the carrier drift velocity are 107 cm/s, then the nominal frequency of the diode is: |
| A. | 12 ghz |
| B. | 25 ghz |
| C. | 30 ghz |
| D. | 24 ghz |
| Answer» C. 30 ghz | |
| 114. |
The resonant frequency of an IMPATT diode is given by: |
| A. | vd/2l |
| B. | vd/l |
| C. | vd/2Ï€l |
| D. | vdd/4Ï€l |
| Answer» B. vd/l | |
| 115. |
If the length of the intrinsic region in IMPATT diode is 2 µm and the carrier drift velocity are 107 cm/s, then the drift time of the carrier is: |
| A. | 10-11 seconds |
| B. | 2×10-11 seconds |
| C. | 2.5×10-11 seconds |
| D. | none of the mentioned |
| Answer» C. 2.5×10-11 seconds | |
| 116. |
To prevent an IMPATT diode from burning, a constant bias source is used to maintain                at safe limit. |
| A. | average current |
| B. | average voltage |
| C. | average bias voltage |
| D. | average resistance |
| Answer» B. average voltage | |
| 117. |
3 IMPATT DIODES, SCHOTTKY BARRIER DIODES, PIN DIODES |
| A. | avalanche multiplication |
| B. | break down of depletion region |
| C. | high reverse saturation current |
| D. | none of the mentioned |
| Answer» B. break down of depletion region | |
| 118. |
The material used to fabricate IMPATT diodes is GaAs since they have the highest efficiency in all aspects. |
| A. | true |
| B. | false |
| Answer» C. | |
| 119. |
In a Gunn diode oscillator, the electron drift velocity was found to be 107 cm/second and the effective length is 20 microns, then the intrinsic frequency is: |
| A. | 5 ghz |
| B. | 6 ghz |
| C. | 4 ghz |
| D. | 2 ghz |
| Answer» B. 6 ghz | |
| 120. |
The frequency of oscillation in Gunn diode is given by: |
| A. | vdom/ leff |
| B. | leff/ vdom |
| C. | leff/ wvdom |
| D. | none of the mentioned |
| Answer» B. leff/ vdom | |
| 121. |
In Gunn diode oscillator, the Gunn diode is inserted into a waveguide cavity formed by a short circuit termination at one end |
| A. | true |
| B. | false |
| Answer» B. false | |
| 122. |
The free electron concentration in N-type GaAs is controlled by: |
| A. | effective doping |
| B. | bias voltage |
| C. | drive current |
| D. | none of the mentioned |
| Answer» B. bias voltage | |
| 123. |
The number of modes of operation for n type GaAs is: |
| A. | two |
| B. | three |
| C. | four |
| D. | five |
| Answer» D. five | |
| 124. |
The modes of operation of a Gunn diode are illustrated in a plot of voltage applied to the Gunn diode v/s frequency of operation of Gunn diode. |
| A. | true |
| B. | false |
| Answer» C. | |
| 125. |
When either a voltage or current is applied to the terminals of bulk solid state compound GaAs, a differential              is developed in that bulk device. |
| A. | negative resistance |
| B. | positive resistance |
| C. | negative voltage |
| D. | none of the mentioned |
| Answer» B. positive resistance | |
| 126. |
The electrodes of a Gunn diode are made of: |
| A. | molybdenum |
| B. | gaas |
| C. | gold |
| D. | copper |
| Answer» B. gaas | |
| 127. |
When the electric field applied to GaAs specimen is less than the threshold electric field, the current in the material: |
| A. | increases linearly |
| B. | decreases linearly |
| C. | increases exponentially |
| D. | decreases exponentially |
| Answer» B. decreases linearly | |
| 128. |
In a GaAs n-type specimen, the current generated is constant irrespective of the electric filed applied to the specimen. |
| A. | true |
| B. | false |
| Answer» C. | |
| 129. |
If a power amplifier has an output power of 10 W, and an amplifier gain of 16.4 dB, then the input drive power is: |
| A. | 400 mw |
| B. | 225 mw |
| C. | 229 mw |
| D. | 240 mw |
| Answer» D. 240 mw | |
| 130. |
If the output power of an amplifier is 10 V, and the input power supplied to the amplifier is 0.229 V given that the DC voltage used is |
| A. | 25% |
| B. | 50% |
| C. | 75% |
| D. | 35% |
| Answer» B. 50% | |
| 131. |
Behavior of a transistor in power amplifiers is unpredictable at all input signal levels. |
| A. | true |
| B. | false |
| Answer» C. | |
| 132. |
A class B amplifier consists of                transistors in order to conduct the input signal over the entire cycle. |
| A. | 1 |
| B. | 2 |
| C. | 4 |
| D. | 6 |
| Answer» C. 4 | |
| 133. |
Gain of power amplifiers                      with increase in operating frequency. |
| A. | increases |
| B. | decreases |
| C. | increases exponentially |
| D. | decreases exponentially |
| Answer» C. increases exponentially | |
| 134. |
Power amplifiers in the increasing order of efficiency is: |
| A. | class a, b, c |
| B. | class c, a, b |
| C. | class b, a, c |
| D. | efficiency of all the 3 amplifiers is the same |
| Answer» B. class c, a, b | |
| 135. |
1 MICROWAVE PASSIVE COMPONENTS: DIRECTIONAL COUPLER, POWER DIVIDER, MAGIC TEE ATTENUATOR, RESONATOR |
| A. | true |
| B. | false |
| Answer» B. false | |
| 136. |
                       amplifiers are linear circuits, where the transistor is biased to conduct over the entire range of the input signal cycle. |
| A. | class a amplifiers |
| B. | class b amplifiers |
| C. | class c amplifiers |
| D. | none of the mentioned |
| Answer» B. class b amplifiers | |
| 137. |
Important factors to be considered for power amplifier design are: |
| A. | efficiency |
| B. | gain |
| C. | thermal effect |
| D. | all of the mentioned |
| Answer» E. | |
| 138. |
                               are used in the final stages of radar and radio transmitters to increase the radiated power level. |
| A. | power amplifiers |
| B. | oscillators |
| C. | transistors |
| D. | attenuators |
| Answer» B. oscillators | |
| 139. |
Which of the following statement about antenna array is false? |
| A. | field pattern is the product of individual elements in array |
| B. | field pattern is the sum of individual elements in array |
| C. | resultant field is the vector superposition of the fields from individual elements in array |
| D. | high directivity can be achieved for long distance communications |
| Answer» C. resultant field is the vector superposition of the fields from individual elements in array | |
| 140. |
What is the progressive phase shift of the end-fire array? |
| A. | 0 |
| B. | 90 c) 180 |
| C. | d) 60 |
| Answer» D. | |
| 141. |
If the progressive shift in antenna array is equal to zero then it is called |
| A. | broad side |
| B. | end-fire |
| C. | yagi-uda |
| D. | fishbone antenna |
| Answer» B. end-fire | |
| 142. |
Total resultant field obtained by the antenna array is given by which of following? |
| A. | vector superposition of individual field from the element |
| B. | maximum field from individual sources in the array |
| C. | minimum field from individual sources in the array |
| D. | field from the individual source |
| Answer» B. maximum field from individual sources in the array | |
| 143. |
The electrical size of antenna is increased by antenna array to avoid size lobes compared to single antenna. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 144. |
For long distance communication, which of the property is mainly necessary for the antenna? |
| A. | high directivity |
| B. | low directivity |
| C. | low gain |
| D. | broad beam width |
| Answer» B. low directivity | |
| 145. |
Electrical size of antenna is increased by which of the following? |
| A. | antenna array |
| B. | decreasing the coverage area |
| C. | increasing the coverage area |
| D. | using a single antenna |
| Answer» B. decreasing the coverage area | |
| 146. |
Which of the following is false about the single antenna for long distance communication? |
| A. | enlarging may create side lobes |
| B. | no side lobes |
| C. | high directivity is required |
| D. | high gain is required |
| Answer» C. high directivity is required | |
| 147. |
Which of the following is false regarding Antenna array? |
| A. | directivity increases |
| B. | directivity decreases |
| C. | beam width decreases |
| D. | gain increases |
| Answer» C. beam width decreases | |
| 148. |
High directivity required in RADAR communication is satisfied using this type of antennas: |
| A. | wide band antennas |
| B. | antenna arrays |
| C. | slot antennas |
| D. | patch antennas |
| Answer» C. slot antennas | |
| 149. |
The terminal impedance of a dipole antenna is 710 Ω. The terminal impedance of the slot antenna given the intrinsic impedance of air is 377 Ω is: |
| A. | 100 Ω |
| B. | 50 Ω |
| C. | 25 Ω |
| D. | none of the mentioned |
| Answer» C. 25 Ω | |
| 150. |
The antennas which offer high operational bandwidth and the antenna parameters are maintained over a wide range of antennas are called: |
| A. | wide band antennas |
| B. | array antennas |
| C. | parabolic antennas |
| D. | none of the mentioned |
| Answer» B. array antennas | |