InterviewSolution
Saved Bookmarks
InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
Modern communication systems useA. analog circuitsB. digital circuitsC. combination of analog & digital circuitsD. radio circuits |
| Answer» Correct Answer - B | |
| 102. |
What does the modern do?A. Modulation onlyB. Demodulation onlyC. Both modulation and demodulationD. Neither modulation nor demodulation |
|
Answer» Correct Answer - C |
|
| 103. |
In AM, the cent percent modulation is achived whenA. Carrier amplitude = signal amplitudeB. Carrier amplitude `ne` signal amplitudeC. Carrier frequency = signal frequencyD. Carrier frequency `ne` signal frequency |
|
Answer» Correct Answer - A |
|
| 104. |
The ratio waves of frequency `300 MHz` to `3000 MHz` belong toA. High frequency bandB. Very high frequency bandC. Ultra high frequency bandD. Super high frequency band |
|
Answer» Correct Answer - C |
|
| 105. |
An antenna behaves as resonant circuit only when its length isA. `(lambda)/(2)`B. `(lambda)/(4)`C. `lambda`D. `(lambda)/(2)` or integral multiple of `(lambda)/(2)` |
|
Answer» Correct Answer - D |
|
| 106. |
A `100 m` long anteena is mounted on a `500 m` tall building. The complex can become a transmission tower for waves with `lambda`.A. `~ 400 m`B. `~ 25 m`C. `~ 150 m`D. `~ 2400 m` |
|
Answer» Correct Answer - A |
|
| 107. |
the attenution in optical fibre is mainly due toA. AbsorptionB. ScatteringC. Neither absorption nor scatteringD. Both (a) and (b) |
|
Answer» Correct Answer - D |
|
| 108. |
The maximum distance upto which ` TV` transmission from a ` TV` tower of height `h` can be received is proportional toA. `(Rh)^((1)/(2))`B. `h`C. `h^(3/2)`D. `h^(2)` |
|
Answer» Correct Answer - A `d=sqrt(2Rh)`, `d prop sqrt(Rh)`, `d prop (Rh)^((1)/(2))` |
|
| 109. |
The maximum distance upto which ` TV` transmission from a ` TV` tower of height `h` can be received is proportional toA. `h^(1//2)`B. hC. `h^(3//2)`D. `h^(2)` |
|
Answer» Correct Answer - A `d=sqrt(2Rh)` |
|
| 110. |
A T.V. tower has a height 150m. What is the population density around the T.V. tower if the total population covered is 50 lakh? (Radius of earth `=6.4xx10^(6)m)`A. `82.6 km^(-2)`B. `800.6 km^(-2)`C. `828.6 km^(-2)`D. `876.6km^(-2)` |
|
Answer» Correct Answer - C `N=sigma pi d^(2)` `50xx10^(5) =sigmaxx22/7xx2xx6.4 xx10^(6) xx150` `sigma=828.6 km^(-2)` |
|
| 111. |
An antennaA. Convrets `AF` wave to `RF` waveB. `RF` signal into electromagnetic energyC. Converts the guided `EM` waves into free space `EM`waves and vice versaD. Super imposes `AF`wave on `RF` wave |
| Answer» Correct Answer - C | |
| 112. |
An antenna is a deviceA. That converts electromagnetic energy into radio frequency signalB. That converts radio frequency signal into electromagnetic energyC. That converts guided electromagnetic waves into free space electromagnetic waves and vice-versaD. None of these |
|
Answer» Correct Answer - C |
|
| 113. |
Device that converts one form of energy into another is calledA. transmitterB. transducerC. receiverD. channel |
| Answer» Correct Answer - B | |
| 114. |
Assertion : Fax is a modulating and demodulating device. Reason : It is necessary for exact reproduction of a document.A. If both assertion and reason are true and the reason is the correct explanation of the assertion.B. If both assertion and reason are true but reason is not the correct explanation of the assertion.C. If assertion is true but reason is false.D. If assertion is false but reason is true. |
|
Answer» Correct Answer - d |
|
| 115. |
An antenna is a deviceA. That converts eletromagnetic energy into radio frequency signalB. That converts radio frequency signal into electromagnetic energyC. That convert guided electomagnetic waves into free space electromagnetic waves and vice-versaD. None of these |
| Answer» Correct Answer - C | |
| 116. |
A transducer used at the transmitting end, serves the purpose of convertingA. electrical signal to sound formB. sound signal to electrical formC. electrical signal to magnetic formD. sound signal to magnetic form |
| Answer» Correct Answer - B | |
| 117. |
A transducer , in communication system in a device thatA. is a part of the antennaB. is a combination of a receiver and a transmitterC. converts audio signals into video signalsD. converts physical variable into corresponding variation in the electical signal |
|
Answer» Correct Answer - D A device that converts variations in a physical quantity such as pressure or brightness into an electrical signal or vice-versa . |
|
| 118. |
Which of the following is not transducer?A. LoudspeakerB. AmplifierC. MicrophoneD. All of these |
|
Answer» Correct Answer - B Transducers are devices which are used to convert one from to energy ( disturbance ) to other form of energy . ( disturbance ) , e.g. Loudspeaker converts electrical energy to sound energy ( mechanical vibrations ). In a microphone , a series of energy conversions occurs in reverse order . One form of energy `to` Transducer `to` Another form of energy Amplifier is a device which increases (amplifies )the amplitude of a signal . In this , the nature of the signal in output and input remains same . |
|
| 119. |
The waves related to telecommuni-cation are-A. visible lightB. infraredC. ultravioletD. microwave |
| Answer» Correct Answer - D | |
| 120. |
An `AM` wave is expressed as `e=10(1+0.6cos2000pit)cos2xx10^(8)pit "volts"`, the minimum and maximum values of modulated carrier wave areA. `10V`, `20V`B. `4V`, `8V`C. `16V`, `4V`D. `8V`, `20V` |
|
Answer» Correct Answer - C `E_(max)=(1+mu)E_(c)` `E_(min)=(1-mu)E_(c)` |
|
| 121. |
The question has statement - 1 and statement - 2 Of the four choices given after the statements , choose the one that best describes the two statements statement - 1 : Sky wave signals are used for long distance radio communication . These signals are in generel , less stable then ground wave signals statement - 2 : The state of inosphere varies from to hour day and season to season .A. both `A`and `B` are trueB. both `A` and `B` are falseC. `A` is true and `B` is falseD. `A` is false and `B` is true |
| Answer» Correct Answer - A | |
| 122. |
Choose the correct statement.A. In the frequency modulation,the amplitude of high frequency carrier wave is mode to vary in proportion to the frequency of audio signal.B. In amplitude modulation, the amplitude of the high frequency carrier wave is made to vary in proportion to the amplitude of the audio signal.C. In amplitude modulation, the frequency or the high frequency carrier wave is made to vary in proportion to the amplitude of audio signal.D. In frequency modulation, the amplitude of the high frequency carrier wave is made to vary in proportion to the amplitude of audio signal. |
| Answer» Correct Answer - B | |
| 123. |
Which of the following is the communication channel in case of radio communication ?A. Free spaceB. Reception linesC. Transmission linesD. None of these |
|
Answer» Correct Answer - A Free space is used as communication channel. |
|
| 124. |
Which of the following is absorbed by the ozone layer ?A. only gamma raysB. visible lightC. radio wavesD. ultraviolet |
|
Answer» Correct Answer - D Ozone present in the layer of atmophere mainly absorbs ultraviolet rays |
|
| 125. |
The wave which are reflected back to the earth by ionosphere isA. ground wavesB. sky wavesC. space waveD. All of them |
|
Answer» Correct Answer - B The ionosphere present in the upper most layer of atmosphere reflects sky waves . |
|
| 126. |
Advantages of optical fibres isA. high band width and EM interferenceB. low band width and EM interferenceC. high band width low transmission capacity and no EM interferenceD. high band width high data transmission capacity and no EM interference |
|
Answer» Correct Answer - D Few advantages of optical fibres are that the number of signals carried by optical fibres is much more than that carried by the Cu wire or radio waves. Optical fibres are practically free from electromagnetic interference and problem of cross talks whereas ordinary cables adn microwaves links suffer a lot from it . |
|
| 127. |
Consider telecommunication through optical fibres. Which of the following statements is not true?A. Optical fibres may have homogeneous core with a suitable claddingB. Optical fibres can be of graded refactive indexC. Optical fibres are subject to electromagnetic interference from outsideD. Optical fibres have extremely low transmission loss |
| Answer» Correct Answer - C | |
| 128. |
The phenomenon by which light travels in an optical fibres isA. ReflectionB. RefractionC. Total internal reflectionD. Transmission |
|
Answer» Correct Answer - C |
|
| 129. |
Consider telecommunication through optical fibres. Which of the following statements is not true?A. Optical fibres may have homogeneous core with a suitable claddingB. Optical fibres can be of graded refractive indexC. Optical fibres are subject to electromagnetic interference from outsideD. Optical fibres have extremely low transmission loss |
|
Answer» Correct Answer - C |
|
| 130. |
Consider telecommunication through optical fibres. Which of the following statements is not true?A. optical fiberes may have homogenous core with a suitable claddingB. optical fibres can be of graded refractive index.C. optical fibres are subjected to electromagnetic interference from outsideD. optical fibres have exteremly low transimmion loss |
|
Answer» Correct Answer - C Optical signals travels in fibre as light. So, they are free from any type of interference. |
|
| 131. |
Audio frequency range is fromA. 20Hz to 20 MHzB. 0 to 2 kHzC. 20 Hz to 20 kHzD. 20 kHz to 200 kHz |
|
Answer» Correct Answer - C The range of audible frequency is from 20Hz to 2o kHz |
|
| 132. |
Which of the following is the disadvantage of `FM` over `AM`A. Larger band width requirementB. Larger noiseC. Higher modulation powerD. Low efficiency |
|
Answer» Correct Answer - A |
|
| 133. |
Fading applies to:A. troposcatter propagationB. ionospheric propagationC. Faraday rotationD. atmospheric storms |
|
Answer» Correct Answer - A In troposcatter propagation signal attenuates (signal strength reduction) with distance. This is known as fading. |
|
| 134. |
Fading is the variation in the strength of a signal at a receiver due toA. interference of wavesB. diffraction of wavesC. polarisation of wavesD. None of these |
|
Answer» Correct Answer - A Fading in the signal received is due to interference of waves . |
|
| 135. |
A sept index fibre has a relavitive refractive index of `0.88%`. What is the critical angle at the core-cladding interface?A. `60^(@)`B. `75^(@)`C. `45^(@)`D. None of these |
|
Answer» Correct Answer - D |
|
| 136. |
The antenna current of an `AM` transmitter is `8A` when only the carrier is sent but increases to `8.96A` when the carrier is modulated sinusoidally . The percentage modulation is |
|
Answer» The modulated or total power carried by `AM` wave `P_(T)=P_(C)(1+(m^(2))/(2))`. If `R` is load resistance. `I_(m)` is the current when carrier is modulated and `I_(c)` the current when unmodulated, then `(P_(T))/(P_(C))=(I_(m)^(2)R)/(I_(c)^(2)R)`, `:. I+(m^(2))/(2)=(I_(m)^(2)R)/(I_(c)^(2)R)` Given `I_(m)=8.93A`, `I_(c)=8A` `:. m^(2)=2[((8.93)/(8.0))^(2)-1]:. m=0.7` Therefore, percentage modulation `=70%` |
|
| 137. |
Range of frequencies allotted for commercial `FM` radio broadcast isA. 88 to 108 MHzB. 88 to 108 KHzC. 8 to 88 MHzD. 88 to 108 GHz |
| Answer» Correct Answer - A | |
| 138. |
An oscillator is producing FM waves of requency `2kHz` with a variation of `10kHz`. What is modulating index?A. 0.2B. 5C. 0.67D. 1.5 |
|
Answer» Correct Answer - B |
|
| 139. |
The maximum peak ro peak voltage of an AM wire is `24 mV` and the minimum peak to peak voltage is `8mV`. The modulation factor isA. `10 %`B. `20%`C. `25%`D. `50%` |
|
Answer» Correct Answer - D |
|
| 140. |
The maximum distance between the transmitting and receving TV towers is `72 km`. If the ratio of the heights of the TV transmitting tower to receiving tower is `16 : 25`, the heights of the transmitting and receiving tower areA. `51.2m`, `80m`B. `40 m` , `80 m`C. `80 m`, `125 m`D. `25 m` , `75 m` |
|
Answer» Correct Answer - C `(h_(t))/(h_(r))=(16)/(25)`, `d=sqrt(2Rh_(t))+sqrt(2Rh_(r))` `72xx10^(3)=sqrt(2R(16)/(25)h_(r))+sqrt(2Rh_(r))` `impliesh_(r)=125m` & `h_(t)=80m` |
|
| 141. |
A T.V. tower has a height of `10 m` is in a region of average population density `100pi//km^(2)`. The number of people that can receive the transmission is nearlyA. `1,28,000`B. `64,000`C. `2,56,000`D. `32,000` |
|
Answer» Correct Answer - A Number of people that can receive `="area"xx"population density"` `=pid^(2)xx"population density"` |
|
| 142. |
The maximum distance between the transmitting and receiving TV towers is `D`. If the heights of both transmitting and receiving towers are doubled then the maximum distance between them becomesA. `2D`B. `sqrt(2)D`C. `4D`D. `D//2` |
|
Answer» Correct Answer - B `s=sqrt(2Rh_(T))+sqrt(2Rh_(R))` when both `h_(T)` and `h_(R)` are doubled then s becomes `sqrt(2) "times"`. |
|
| 143. |
A T.V. tower has a height of `5 m` is in a region of average population density `100pi//km^(2)`. The number of people that can receive the transmission is nearlyA. `1,28.000`B. `64000`C. `2,56,000`D. `32,000` |
|
Answer» Correct Answer - B `A=piD^(2)=pi[2Rh_(2)]` `n=("Population density")A` |
|
| 144. |
At certain distance from a transmitting tower a receiver tower of height `180m` is used to receive direct signal. Another tower is installed beyond the first along the same line of sight to receive the signals from the same transmitter. Its height is `21%` more than the first receiving tower. Then the separation between the two receiving towers isA. `6.4 km`B. `3.2 km`C. `1.6 km`D. `4.8 km` |
|
Answer» Correct Answer - D `d=sqrt(2Rh_(2))-sqrt(2Rh_(1))`, `h_(2)=h_(1)-21%` of `h_(1)` |
|
| 145. |
The TV signals have a band width of `4MHz`.The number of TV channels that can be accommodated in a band width `16GHz` isA. `2`B. `20`C. `200`D. `4000` |
|
Answer» Correct Answer - D `n=(16GHz)/(4MHz)` |
|
| 146. |
Modulation is required to (`a`) distinguish different transmissions (`b`) ensure that the information may be transmitted over long distances (`c`) allow the information accessible for different peopleA. `a` & `b` are trueB. `b` & `c `are trueC. `c` & `a ` are trueD. `a`, `b`, `c` are true |
| Answer» Correct Answer - D | |
| 147. |
Band width of an optical fiber isA. more than `100 GHz`B. few `KHz`C. less than `1 MHz`D. less than `1GHz` |
| Answer» Correct Answer - A | |
| 148. |
The tuned circuit of an oscillator in a simple `AM` transimitter employs a `250` micro henry coil and `1 nf` condenser. If the oscillartor output is modulated by audio frequency upto `10KHz`, the frequency range occupied by the side bands in `KHz` isA. `210` to `230`B. `258` to `278`C. `308` to `328`D. `118` to `128` |
|
Answer» Correct Answer - C `f_(c)=(1)/(2pisqrt(LC))=318 khz`, `f_(m)=10khz` `LSB=f_(c)-f_(m)=308` `USB=f_(c)+f_(m)=328` |
|
| 149. |
The physical quantities of the wave used for modulationA. Amplitude onlyB. Amplitude and frequencyC. Amplitude , frequency and phaseD. Only frequency |
| Answer» Correct Answer - C | |
| 150. |
Frequency ranges for micro waves are:A. `3xx10^(9)` to `3xx10^(4)Hz`B. `3xx10^(13)` to `3xx10^(9)Hz`C. `3xx10^(14)` to `3xx10^(9)Hz`D. `3xx10^(11)` to `3xx10^(9)Hz` |
| Answer» Correct Answer - B | |