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MCQOPTIONS
This section includes 1362 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.
| 1151. |
c(t) and m(t) are used to generate an AM signal. The modulation index of the generated AM signal is 0.5 then the quantity is |
| A. | 43497 |
| B. | 43556 |
| C. | 43525 |
| D. | 43678 |
| Answer» E. | |
| 1152. |
Skip distance depends on time of day and angle of incidence. |
| A. | 1 |
| B. | |
| C. | 150 kHz |
| D. | 100 kHz |
| Answer» B. | |
| 1153. |
In frequency modulation noise can be further reduced by |
| A. | increasing deviation |
| B. | reducing deviation |
| C. | reducing carrier frequency |
| D. | increasing signal amplitude |
| Answer» B. reducing deviation | |
| 1154. |
Which of the following circuits cannot be demodulate SSB? |
| A. | Product detector |
| B. | Balanced modulator |
| C. | Phase discriminator |
| D. | BFO |
| Answer» D. BFO | |
| 1155. |
MTSO stands for |
| A. | Metropolitan Telecommunication Subscribers Office |
| B. | Metropolitan Telecommunication Switching Office |
| C. | Mobile Telecommunication Switching Office |
| D. | Mobile Telecommunication Subscriber Office |
| Answer» D. Mobile Telecommunication Subscriber Office | |
| 1156. |
A directional microphone gives an output of 0.5 mV whereas an omnidirectional one gives an output of 0.5 μV in the same position for the same sound pressure. The directivity of the directional microphone is |
| A. | 120 dB |
| B. | 90 dB |
| C. | 60 dB |
| D. | 30 dB |
| Answer» D. 30 dB | |
| 1157. |
In the equivalent circuit of a moving coil cone type loudspeaker, the mass of the moving system is represented by |
| A. | a resistance |
| B. | a capacitance |
| C. | an inductance |
| D. | a conductance |
| Answer» D. a conductance | |
| 1158. |
In an end fire array, the radiation pattern |
| A. | is in the plane of array |
| B. | is at right angles to array |
| C. | is at an angle to the plane of array |
| D. | either (b) or (c) |
| Answer» B. is at right angles to array | |
| 1159. |
Hue of a colour means |
| A. | amount of light energy received by eye |
| B. | predominant spectral purity of colour light |
| C. | amount of other colours present |
| D. | none of the above |
| Answer» C. amount of other colours present | |
| 1160. |
The PSD and the power of a signal g(t) are respectively Sg(ω) and Pg, the PSD and the power of signal a.g(t) are respectively |
| A. | aS2g (ω) and a2Pg |
| B. | aSg2 (ω) and aPg |
| C. | aSg (ω) and a2Pg |
| D. | aSg (ω) and aPg |
| Answer» B. aSg2 (œâ) and aPg | |
| 1161. |
A CW transmitter radiates |
| A. | modulated RF carrier |
| B. | unmodulated RF carrier |
| C. | both (a) and (b) |
| D. | none of the above |
| Answer» B. unmodulated RF carrier | |
| 1162. |
It is found that in a telephone system 60 subscribers initiate calls during a 30 minute interval and the total duration of all the calls is 100 minutes. The load is |
| A. | 2 |
| B. | 3 erlang |
| C. | 3.333 erlang |
| D. | 0.333 erlang |
| Answer» D. 0.333 erlang | |
| 1163. |
In AM increased depth of modulation increases __________ and in FM with increased depth of modulation __________ increases. |
| A. | total transmitted power, bandwidth |
| B. | bandwidth, bandwidth |
| C. | bandwidth, total transmitted power |
| D. | total transmitted power, sideband power |
| Answer» B. bandwidth, bandwidth | |
| 1164. |
Which of the following amplifiers is used for impedance matching? |
| A. | CE |
| B. | CC |
| C. | CB |
| D. | Push pull |
| Answer» C. CB | |
| 1165. |
The depth of modulation is doubled in FM system then, the power transmitted |
| A. | increase by factor of 2 |
| B. | increase by factor of 3 |
| C. | increase by factor of 2 |
| D. | none of the above |
| Answer» E. | |
| 1166. |
If a dipole is meant for a frequency of 1 MHz, the length of each rod is about |
| A. | 5 m |
| B. | 20 m |
| C. | 100 m |
| D. | 50 m |
| Answer» E. | |
| 1167. |
If S represents the carrier synchronization at the receiver and r represents the bandwidth efficiency, then the correct statement for the coherent binary PSK is |
| A. | r = 0.5, S is required |
| B. | r = 1.0, S is required |
| C. | r = 0.5, S is not required |
| D. | r = 1.0, S is not required |
| Answer» E. | |
| 1168. |
The resonant frequency of an RF amplifier is 1 MHz and its bandwidth is 10 kHz. The Q factor will be |
| A. | 10 |
| B. | 100 |
| C. | 0.01 |
| D. | 0.1 |
| Answer» C. 0.01 | |
| 1169. |
Human ear can detect sound intensities of the order of |
| A. | 10-4 W/m2 |
| B. | 10-8 W/m2 |
| C. | 10-13 W/m2 |
| D. | 10-18 W/m2 |
| Answer» D. 10-18 W/m2 | |
| 1170. |
For TV broadcast, picture signal is modulated in |
| A. | SSB |
| B. | VSB |
| C. | FM |
| D. | AM |
| Answer» E. | |
| 1171. |
Brownian motion is |
| A. | random emission of electrons in vacuum tubes |
| B. | thermal motion of electrons in a resistance |
| C. | random diffusion of holes and electrons in semi- conductors |
| D. | both (b) and (c) |
| Answer» C. random diffusion of holes and electrons in semi- conductors | |
| 1172. |
BPSK stands for |
| A. | Binary Phase Shifting Key |
| B. | Broad Phase Shifting Key |
| C. | Bit Phase Shifting Key |
| D. | Binary Pulse Shifting Key |
| Answer» B. Broad Phase Shifting Key | |
| 1173. |
Which of the following is not considered as a useful quantity in comparing noise performance of receivers? |
| A. | Noise temperature |
| B. | Noise figure |
| C. | Noise resistance |
| D. | Input noise voltage |
| Answer» E. | |
| 1174. |
The time required for horizontal blanking is 16% of that for each horizontal line. If horizontal time is 63.5 μs, the horizontal blanking time for each line is about |
| A. | 1 μs |
| B. | 10 μs |
| C. | 100 μs |
| D. | none of the above |
| Answer» C. 100 Œºs | |
| 1175. |
The output VR of the ratio detector is related with the output VF of similar Foster-Seeley discriminator as follows. |
| A. | VR = VF |
| B. | VR < VF |
| C. | VR = 2VF |
| D. | VF = 2VR |
| Answer» D. VF = 2VR | |
| 1176. |
The most commonly used transistor amplifier circuit is |
| A. | CB |
| B. | CC |
| C. | CE |
| D. | CE or CC |
| Answer» D. CE or CC | |
| 1177. |
A discrete zero memory information source has 40 symbols and each symbol is equally likely. The minimum number of bits required to code the source with uniform length code and entropy of the source are |
| A. | 5 and 5.03 |
| B. | 6 and 5.83 |
| C. | 5 and 6.64 |
| D. | 6 and 5.32 |
| Answer» E. | |
| 1178. |
The distance of a direct broadcasting satellite from earth's surface is about |
| A. | 1000 km |
| B. | 10000 km |
| C. | 36000 km |
| D. | 55000 km |
| Answer» D. 55000 km | |
| 1179. |
Linear diode detector utilizes |
| A. | linear portion of static characteristics of diode |
| B. | linear portion of dynamic characteristic of diode |
| C. | square law portion of dynamic characteristics of diode |
| D. | rectification property of diode |
| Answer» E. | |
| 1180. |
How much is contributed by each bit in the code word of a PCM system under uniform and symmetric quantization to the signal to noise ratio? |
| A. | 3 dB |
| B. | 4 dB |
| C. | 5 dB |
| D. | 6 dB |
| Answer» E. | |
| 1181. |
FM has poor efficiency than |
| A. | AM |
| B. | AM-SC |
| C. | PAM |
| D. | PCM |
| Answer» C. PAM | |
| 1182. |
Consider the following statements The amplitude of an FM wave is constantFM is more immune to noise than AMFM broadcasts operate in upper VHF and UHF frequency rangesFM transmitting and receiving equipments are simpler as compared to AM transmitting and receiving equipments Which of the above are correct? |
| A. | 1, 2, 3, 4 |
| B. | 1, 2, 3 |
| C. | 2, 3, 4 |
| D. | 1, 3, 4 |
| Answer» C. 2, 3, 4 | |
| 1183. |
In the human eye, an image persists for a time of about |
| A. | 1 second |
| B. | 0.1 second |
| C. | 0.05 second |
| D. | 0.02 second |
| Answer» E. | |
| 1184. |
Assertion (A): For satellites and space probes, PRF of a radar is pretty low.Reason (R): PRF of a radar depends on the range of a radar. |
| 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 | |
| 1185. |
Which of the following microphones has an inbuilt amplifier? |
| A. | Condenser |
| B. | Moving coil |
| C. | Ribbon |
| D. | Carbon |
| Answer» B. Moving coil | |
| 1186. |
Satellites used for international communication are called |
| A. | cossort |
| B. | domsat |
| C. | marisat |
| D. | intelsat |
| Answer» E. | |
| 1187. |
Consider the following features of monochrome TV Number of lines per picture 625Interlace ratio 2 : 1Aspect ratio 4 : 3Channel bandwidth 8 MHz As regards CCIR system B, which of the above are correct? |
| A. | 1, 2, 3, 4 |
| B. | 1, 2, 3 |
| C. | 1, 2, 4 |
| D. | 2, 3, 4 |
| Answer» C. 1, 2, 4 | |
| 1188. |
In communication systems, the modulating signal is also called |
| A. | base band signal |
| B. | side bands |
| C. | auxiliary signal |
| D. | none of the above |
| Answer» B. side bands | |
| 1189. |
An earth mat for a communication tower consists of |
| A. | one or two radials extending from base of tower at a depth of about 5 cm below ground |
| B. | a large number of radials extending from base of tower at a depth of about 3 m |
| C. | a large number of radials extending from base of tower at a depth of about 30 cm |
| D. | none of the above |
| Answer» D. none of the above | |
| 1190. |
A horizontal output stage is cutoff for retrace and 40% of trace. If time for each horizontal line is 64 μs and retrace time is 12 μs, the transistor is conducting for about |
| A. | 64 μs |
| B. | 6.4 μs |
| C. | 31 μs |
| D. | 3.1 μs |
| Answer» D. 3.1 Œºs | |
| 1191. |
On modulating a carrier of frequency fc by an audio signal fs, the following components has resulted: fc, fc + fs and fc - fs What is this type of modulation likely to be? |
| A. | Amplitude modulation (DSB) |
| B. | Single sideband modulation |
| C. | Frequency modulation only |
| D. | Amplitude modulation or frequency modulation |
| Answer» B. Single sideband modulation | |
| 1192. |
A narrow band noise n(t) has symmetrical spectrum and has power density spectrum 0.2 x 10-6. The power density of quadrature component is |
| A. | 0.2 x 10-6 |
| B. | 43656 |
| C. | 4 x 10-7 |
| D. | 5 x 10-8 |
| Answer» C. 4 x 10-7 | |
| 1193. |
Which of the following oscillator is not in FM? |
| A. | Crystal oscillator |
| B. | Hartley oscillator |
| C. | Colpitts oscillator |
| D. | All of the above |
| Answer» C. Colpitts oscillator | |
| 1194. |
Which of the following terms is not applicable to Yagi-Uda array? |
| A. | High gain |
| B. | Folded dipole |
| C. | Parasitic elements |
| D. | Good bandwidth |
| Answer» B. Folded dipole | |
| 1195. |
An antenna has a resistance of 50 Ω and an equivalent noise resistance of 30 Ω The noise figure in decibels is |
| A. | 1.6 dB |
| B. | 2 dB |
| C. | 3.6 dB |
| D. | 6 dB |
| Answer» C. 3.6 dB | |
| 1196. |
The receiver of a pulsed RADAR can detect signal power in the order of |
| A. | 1 W |
| B. | 0.1 W |
| C. | 10-5 W |
| D. | 10-12 W |
| Answer» E. | |
| 1197. |
If the frequency of a wave 20 Hz, the time period is |
| A. | 20 secs |
| B. | 2 secs |
| C. | 0.2 secs |
| D. | 0.05 secs |
| Answer» E. | |
| 1198. |
In cell communication |
| A. | carrier frequency change |
| B. | carrier frequency constant |
| C. | depend upon location |
| D. | depend upon geographical area |
| Answer» B. carrier frequency constant | |
| 1199. |
Pulse modulation is often used in |
| A. | microwave band |
| B. | FL band |
| C. | telegraphy |
| D. | telephony |
| Answer» D. telephony | |
| 1200. |
In FM, the frequency deviation is |
| A. | always constant |
| B. | directly proportional to modulating frequency |
| C. | inversely proportional to modulating frequency |
| D. | proportional to amplitude of modulating signal |
| Answer» E. | |