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MCQOPTIONS
This section includes 9294 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 7851. |
An AM wave is given by s(t)AM = 20 (1 + 0.5 cos 103t + 0.3 cos 104 t cos 106 t) the modulation index of the envelope is |
| A. | 0.5 |
| B. | 0.58 |
| C. | 0.3 |
| D. | 0.8 |
| Answer» C. 0.3 | |
| 7852. |
The modulating frequency in frequency modulation is increased from 10 kHz to 30 kHz. The bandwidth is increased by |
| A. | 6 |
| B. | 1/6 times |
| C. | increase by 30 kHz |
| D. | increase by 20 kHz |
| Answer» B. 1/6 times | |
| 7853. |
Three point tracking is achieved with |
| A. | double conversion |
| B. | padder capacitor |
| C. | double spotting |
| D. | variable selectivity |
| Answer» C. double spotting | |
| 7854. |
In TV transmitter, visual exciter may consist of Video processing unitVisual modulatorVSB filterDelay equaliserFrequency converter Which of the above are actually a part of visual exciter? |
| A. | 1, 2 and 3 |
| B. | 2, 3 and 4 |
| C. | 1, 2, 3 and 4 |
| D. | 1, 2, 3, 4 and 5 |
| Answer» E. | |
| 7855. |
An AM signal is detected using an envelope detector, the carrier frequency and modulating signal frequency are 1 MHz and 2 kHz respectively. An appropriate value for the time constant of the envelope detector is |
| A. | 500 sec |
| B. | 20 sec |
| C. | 0.2 sec |
| D. | 1 sec |
| Answer» C. 0.2 sec | |
| 7856. |
If transmitted power is 10 kW, the field strength at a distance d is 50 mV/m. If transmitted power is reduced to 2.5 kW, the field strength at the same point will be |
| A. | 25 mV/m |
| B. | 12.5 mV/m |
| C. | 6.25 mV/m |
| D. | 3.125 mV/m |
| Answer» B. 12.5 mV/m | |
| 7857. |
The carrier frequency will be if L = 50 H and C = 1 nF. |
| A. | 512 |
| B. | 612 kHz |
| C. | 712 kHz |
| D. | 812 kHz |
| Answer» D. 812 kHz | |
| 7858. |
A 1000 kHz carrier is simultaneously modulated by 300 Hz and 2 kHz audio sine wave. Which of the following frequencies will not be present in the output? |
| A. | 998 kHz |
| B. | 999.7 kHz |
| C. | 1000.3 kHz |
| D. | 700 kHz |
| Answer» E. | |
| 7859. |
SWR for a transmission line is infinity when the load is Short circuitComplex impedanceOpen circuitPure reactance Of the above statements: |
| A. | 1, 3, 4 are correct |
| B. | 1 and 3 are correct |
| C. | 2, 3, 4 are correct |
| D. | 1, 2, 4 are correct |
| Answer» B. 1 and 3 are correct | |
| 7860. |
Some features of advanced mobile phone service are To provide telephone communication to a large number of telephone users within the area of a metropolitan onlyTo use minimum amount of frequency spectrumTo permit hand held as well as vehicle operation of telephone Which of the above are true? |
| A. | 1 and 2 only |
| B. | 1, 2, 3 |
| C. | 1 and 3 only |
| D. | 2 and 3 only |
| Answer» C. 1 and 3 only | |
| 7861. |
The discone antenna is |
| A. | used in UHF range |
| B. | circularly polarized |
| C. | used in radar |
| D. | used as a direction finding antenna |
| Answer» B. circularly polarized | |
| 7862. |
A (75 - j 50) Ω load is connected to a coaxial line of Z0 = 75 Ω at 10 GHz. The best method of matching consists of using |
| A. | a capacitance at some specific distance from load |
| B. | a short circuited stub at some specific distance from load |
| C. | an inductance at load |
| D. | a short circuited stub at load |
| Answer» E. | |
| 7863. |
Compact discs use |
| A. | magnetic recording and retrieval |
| B. | optical recording and retrieval |
| C. | optical recording but magnetic retrieval |
| D. | magnetic recording but optical retrieval |
| Answer» C. optical recording but magnetic retrieval | |
| 7864. |
The direction of pick up in a CD is |
| A. | linear from centre towards edge |
| B. | linear from edge to centre |
| C. | nonlinear from centre to edge |
| D. | nonlinear from edge to center |
| Answer» B. linear from edge to centre | |
| 7865. |
A carrier is phase modulated (PM) with frequency deviation of 10 kHz by a single tone frequency of 1 kHz. If the single tone frequency is increased to 2 kHz, assuming that phase deviation remains unchanged, the bandwidth of the PM signal is |
| A. | 21 kHz |
| B. | 22 kHz |
| C. | 42 kHz |
| D. | 44 kHz |
| Answer» E. | |
| 7866. |
In a communication receiver, a squelch circuit is normally inserted |
| A. | before detector |
| B. | after detector |
| C. | before mixer |
| D. | after power amplifier |
| Answer» C. before mixer | |
| 7867. |
In PCM, the information lies |
| A. | in one or two properties of the pulse |
| B. | in absence of pulse |
| C. | in presence of pulse |
| D. | in presence or absence of pulse |
| Answer» E. | |
| 7868. |
Two sinusoidal signals of same amplitude and frequencies 10 kHz and 10.1 kHz are added together. The combined signal is given to an ideal frequency detector. The output of the detector is |
| A. | 0.1 kHz sinusoidal |
| B. | 10.1 kHz sinusoidal |
| C. | a linear function |
| D. | a constant |
| Answer» C. a linear function | |
| 7869. |
In Vidicon camera tube, the resistance of photoconductive material on the target plate |
| A. | is constant |
| B. | is more in darkness and less in brightness |
| C. | is more in brightness but less in darkness and brightness |
| D. | may be more or less in darkness and brightness |
| Answer» C. is more in brightness but less in darkness and brightness | |
| 7870. |
Which of the following are useful in comparing the noise performance of receivers? Input noise voltageNoise figureNoise resistanceNoise temperature Select answer as per the following codes: |
| A. | 1, 2 and 3 |
| B. | 1, 3 and 4 |
| C. | 2, 3, 4 |
| D. | 1, 2, 4 |
| Answer» D. 1, 2, 4 | |
| 7871. |
Which of the following antennas is circularly polarized? |
| A. | Yagi-Uda |
| B. | Parabolic reflector |
| C. | Small circular loop |
| D. | Helical |
| Answer» E. | |
| 7872. |
In colour TV system the colour sub carrier frequency is 4.43 MHz. |
| A. | True |
| B. | False |
| Answer» C. | |
| 7873. |
A transmitter power of 5 W is increased by 20 dB. The effective radiated power is |
| A. | 5 W |
| B. | 100 W |
| C. | 25 W |
| D. | 500 W |
| Answer» E. | |
| 7874. |
The percentage saving in power of 100% modulated suppressed carrier AM signal is |
| A. | 100 |
| B. | 75 |
| C. | 66.6 |
| D. | 50 |
| Answer» D. 50 | |
| 7875. |
The maximum distance between television transmission and receiving antennas for reasonably good reception should be |
| A. | less than 20 km |
| B. | less than 100 km |
| C. | less than 500 km |
| D. | less than 1000 km |
| Answer» C. less than 500 km | |
| 7876. |
The total number of pulses in a TV remote control is |
| A. | 14 |
| B. | 12 |
| C. | 10 |
| D. | 8 |
| Answer» B. 12 | |
| 7877. |
Which camera tube has highest sensitivity and very wide spectral response? |
| A. | Vidicon |
| B. | Plumbicon |
| C. | New vicon |
| D. | Saticon |
| Answer» D. Saticon | |
| 7878. |
A computer monitor uses 180 W in normal operation and 20 W in sleep mode. The computer is on all the 24 hours but is in sleep mode for 18 hours a days. The energy units saved in 30 days are |
| A. | 0.54 units |
| B. | 86.4 units |
| C. | 2.88 units |
| D. | 4.8 units |
| Answer» C. 2.88 units | |
| 7879. |
Consider the following functions It detects the AM video carrier IF so as to produce the video signalIt produces and separates out the inter carrier sound IF of 5.5 MHzIt amplifies the video signalIt amplifies the audio signal The video detector in a colour TV performs which of the above functions |
| A. | 1, 2 and 3 |
| B. | 1, 2, 3 and 4 |
| C. | 1 and 2 |
| D. | 1, 2 and 4 |
| Answer» D. 1, 2 and 4 | |
| 7880. |
Assertion (A): EM waves are attenuated as they travel outward from a sourceReason (R): Both field intensity and power density follow inverse square law. |
| 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» B. Both A and R are correct but R is not correct explanation of A | |
| 7881. |
Assertion (A): A Smith chart can be used for a number of calculations of a transmission lineReason (R): Smith chart is basically a polar impedance diagram. |
| 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 | |
| 7882. |
The frequency response of a microphone means |
| A. | bandwidth of frequencies having output with in 1 dB of the output at 1000 Hz |
| B. | bandwidth of frequencies having output with in 3 dB of the output at 1000 Hz |
| C. | bandwidth of frequencies having output with in 1 dB of the output at 500 Hz |
| D. | bandwidth of frequencies having output with in 3 dB of the output at 500 Hz |
| Answer» B. bandwidth of frequencies having output with in 3 dB of the output at 1000 Hz | |
| 7883. |
An amplifier operating over a frequency range of 18 to 20 MHz has 10 kΩ input resistance. At a temperature of 27 C, the noise voltage at input of amplifier is (Boltzman constant k = 1.38 x 10-23 J/K) |
| A. | 18.2 V |
| B. | 182 V |
| C. | 16.2 V |
| D. | 162 V |
| Answer» B. 182 V | |
| 7884. |
Some sources of TV programs are TV cameraTelecineVTRExternal signal Which of the above are actually present in a TV studio? |
| A. | 1, 2, 3 and 4 |
| B. | 1, 2, 3 |
| C. | 1 and 3 |
| D. | 1 2 and 4 |
| Answer» B. 1, 2, 3 | |
| 7885. |
Graphic equaliser system in stereophonic systems generally have |
| A. | 3 or 4 bands |
| B. | 1 band |
| C. | more than 8 bands |
| D. | large number of bands |
| Answer» B. 1 band | |
| 7886. |
A TV receiver is 40 cm wide and 30 cm high. The EHT supply required is about |
| A. | 2kV |
| B. | 20 kV |
| C. | 53 kV |
| D. | 10 W |
| Answer» C. 53 kV | |
| 7887. |
In PCM the amplitude levels are transmitted in a 7 unit code. Sampling frequency is 10 kHz. The bandwidth should be |
| A. | 5 kHz |
| B. | 35 kHz |
| C. | 70 kHz |
| D. | 5 MHz |
| Answer» C. 70 kHz | |
| 7888. |
In colour television V and U signals are |
| A. | same as I and Q signal |
| B. | same as R - Y and B - Y |
| C. | modified I and Q signal |
| D. | modified R - Y and B - Y |
| Answer» E. | |
| 7889. |
Two messages m1, and m2 have a probability of 0.5 each. The entropy is |
| A. | 0.25 |
| B. | 0.5 |
| C. | 0.75 |
| D. | 1 |
| Answer» E. | |
| 7890. |
Which of the following has highest power gain? |
| A. | CE |
| B. | CC |
| C. | CB |
| D. | CB or CC |
| Answer» B. CC | |
| 7891. |
A resistor of 10 kΩ has an rms noise voltage of 1 mV under a certain set of conditions. A resistor of 20 kΩ under the same conditions will have an rms noise voltage of |
| A. | 1 mV |
| B. | 2 mV |
| C. | 1.414 mV |
| D. | 4 mV |
| Answer» D. 4 mV | |
| 7892. |
The positive peak of an AM wave is 16 V and the minimum value is 4 V Assuming single tone modulation, the modulation index is |
| A. | 0.6 |
| B. | 0.25 |
| C. | 4 |
| D. | 0.36 |
| Answer» B. 0.25 | |
| 7893. |
In a circuit the value of resistor is made four times. The noise voltage generated by this resistance will |
| A. | be doubled |
| B. | be increased four times |
| C. | remain the same |
| D. | become half |
| Answer» B. be increased four times | |
| 7894. |
In the television system in India, the odd and even fields are scanned |
| A. | 25 times each |
| B. | 25 times each but alternately |
| C. | 50 times each |
| D. | 50 times each but alternately |
| Answer» C. 50 times each | |
| 7895. |
Consider the following A signal f(t) and its Hilbert transform fh(t) have the same energy density spectrumA signal f(t) and its Hilbert transform, fh(t) have the same auto correlation functionA signal f(t) and its Hilbert transform are mutually orthogonal Which of the above are true? |
| A. | 1, 2 and 3 |
| B. | 1 and 2 only |
| C. | 1 only |
| D. | 2 and 3 only |
| Answer» B. 1 and 2 only | |
| 7896. |
The typical squelch circuit |
| A. | cuts off IF amplifier when AGC is minimum |
| B. | cuts off IF amplifier when AGC is maximum |
| C. | cuts off audio amplifier when carrier is absent |
| D. | eliminates RF interference when signal is weak |
| Answer» D. eliminates RF interference when signal is weak | |
| 7897. |
Vidicon and plumbicon operate on the principle of |
| A. | photo conduction |
| B. | photo emission |
| C. | photo voltaic |
| D. | none of the above |
| Answer» B. photo emission | |
| 7898. |
A TV receiver has a width of 60 cm. The aspect ratio is 4/3. The required EHT supply is about |
| A. | 29 kV |
| B. | 2.9 kV |
| C. | 45 kV |
| D. | 4.5 kV |
| Answer» B. 2.9 kV | |
| 7899. |
A balun provides an impedance transformation of |
| A. | 16 : 1 |
| B. | 8 : 1 |
| C. | 4 : 1 |
| D. | 2 : 1 |
| Answer» D. 2 : 1 | |
| 7900. |
If = (S0/N0)/(Si/Nm) where S0 and S1 are signal power output and signal power input and N0 and Nm are noise power output and noise power input, the value of for SSB-SC and DSB-SC amplitude modulated system respectively are |
| A. | 1 and 1 |
| B. | 1 and 2 |
| C. | 2 and 1 |
| D. | 0.5 and 0.5 |
| Answer» B. 1 and 2 | |