MCQOPTIONS
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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.
| 951. |
Which of the following sampling frequencies is considered adequate in voice telephony? |
| A. | 4 kHz |
| B. | 8 kHz |
| C. | 16 kHz |
| D. | 32 kHz |
| Answer» C. 16 kHz | |
| 952. |
A geostationary satellite |
| A. | is located at a height of 358, 00 km |
| B. | appears stationary over earth's magnetic pole |
| C. | is motionless in space but keeps spinning |
| D. | orbits the earth within a 24 hour period |
| Answer» E. | |
| 953. |
Assertion (A): The colour signal consists of only luminance signalReason (R): In India PAL colour signal system is used. |
| 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» E. | |
| 954. |
Pilot-carrier transmission is one in which |
| A. | only one sideband is transmitted |
| B. | one sideband and carrier are transmitted |
| C. | only two sidebands are transmitted |
| D. | two sidebands as well as a trace of carrier are transmitted |
| Answer» E. | |
| 955. |
The characteristic impedance of coaxial cable is about |
| A. | 1000 ohm |
| B. | 500 ohm |
| C. | 250 ohm |
| D. | 75 ohm |
| Answer» E. | |
| 956. |
A 5000 W signal is attenuated by - 196 dB. The resultant signal strength is |
| A. | 1.26 x 106 W |
| B. | 1.26 x 10-2 W |
| C. | 1.26 x 10-8 W |
| D. | 1.26 x 10-16 W |
| Answer» E. | |
| 957. |
In a TV studio the illuminance is about |
| A. | 200 lux |
| B. | 1000 lux |
| C. | 10000 lux |
| D. | 10 lux |
| Answer» C. 10000 lux | |
| 958. |
The distance at which a sky wave is received back on earth decreases with angle of incidence for all angles of incidence. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 959. |
In FM, when the bandwidth is doubled, the signal to noise ratio improves by a factor of |
| A. | 2 dB |
| B. | 4 dB |
| C. | 6 dB |
| D. | 8 dB |
| Answer» D. 8 dB | |
| 960. |
In the output of a DM speech encoder, the consecutive pulses are of opposite polarity during time interval t1 < t < t2. This indicates that during this interval |
| A. | the input to the modulator is essentially constant |
| B. | the modulator is going through slope overload |
| C. | the accumulator is in saturation |
| D. | the speech signal is being sampled at the Nyquist rate |
| Answer» B. the modulator is going through slope overload | |
| 961. |
In a tape recorder |
| A. | both record and erase heads have high permeability core |
| B. | the record head has high permeability core but the erase head has low permeability core |
| C. | the record head has low permeability core but the erase head has high permeability core |
| D. | both record and erase heads have low permeability core |
| Answer» B. the record head has high permeability core but the erase head has low permeability core | |
| 962. |
An analog signal is band limited to B Hz sampled at Nyquist rate and samples are quantized into 4 levels each with probability . The information rate is |
| A. | 4 bits/s |
| B. | B bits/s |
| C. | 4 B bits/s |
| D. | 0.25 B bits/s |
| Answer» D. 0.25 B bits/s | |
| 963. |
Assertion (A): Demodulation of SSB and AM signals is exactly similar Reason (R): The basic SSB demodulation device is product detector. |
| 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» E. | |
| 964. |
The amplitude of a modulated RF aerial current is 6 A on the peaks of modulation and 4 A on the troughs of modulation. The value of carrier amplitude is |
| A. | 5 |
| B. | 15 |
| C. | 20 |
| D. | 30 |
| Answer» B. 15 | |
| 965. |
For a resistance of about 15 kΩ operating in a frequency range of a few MHz, the noise voltage is in the range of |
| A. | a few μV |
| B. | about 100 μV |
| C. | a few μV |
| D. | a few volts |
| Answer» B. about 100 ŒºV | |
| 966. |
Which of the following amplifiers has highest output impedance? |
| A. | CE |
| B. | CB |
| C. | CC |
| D. | Push pull |
| Answer» C. CC | |
| 967. |
Thermal noise Power is |
| A. | proportional to bandwidth (B) |
| B. | ‚àù B |
| C. | |
| Answer» B. ‚àù B | |
| 968. |
A pure tone at 1000 Hz has a dB level of 50 dB. If two such tones exist simultaneously the dB level is about |
| A. | 50 dB |
| B. | 53 dB |
| C. | 100 dB |
| D. | 200 dB |
| Answer» C. 100 dB | |
| 969. |
Typical value of power consumption of TV transmitter is |
| A. | 0.5 kVA |
| B. | 2 kVA |
| C. | 50 kVA |
| D. | 1000 kVA |
| Answer» D. 1000 kVA | |
| 970. |
In radar PRF depends on maximum range. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 971. |
If γ = (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 γ 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 | |
| 972. |
Consider the following statements about PCM PCM is not noise resistantPCM requires complex encoding and quantizing circuitryPCM requires large bandwidth Which of the above are correct? |
| A. | 1 only |
| B. | 1, 2, 3 |
| C. | 2, 3 |
| D. | 1 and 3 |
| Answer» D. 1 and 3 | |
| 973. |
Assertion (A): If a carrier is modulated by three sine waves and m1, m2, m3 are the modulation indices, the total modulation index mt is mt = (m12 + m22 + m32)0.5Reason (R): An AM, higher the level of modulation, lower is the audio power required to produce modulation. |
| 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» D. A is wrong but R is correct | |
| 974. |
In the above case the modulation index will be |
| A. | 9.6 |
| B. | 28.8 |
| C. | 57.6 |
| D. | 100 |
| Answer» E. | |
| 975. |
The function of blend control in stereo system is |
| A. | to dilute left channel |
| B. | to dilute right channel |
| C. | to dilute any of the channels |
| D. | none of the above |
| Answer» D. none of the above | |
| 976. |
The most commonly used microphone for public address systems is |
| A. | carbon |
| B. | crystal |
| C. | moving coil |
| D. | condenser |
| Answer» D. condenser | |
| 977. |
Waves of frequencies higher than 30 MHz penetrate the atmosphere. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 978. |
A 1000 kHz carrier is simultaneously modulated with 300 Hz, 800 Hz and 2 kHz audio sine waves. The frequencies present in the output will be |
| A. | 998 kHz and 1002 kHz |
| B. | 998 kHz, 999.2 kHz, 1000.8 kHz, 1002.0 kHz |
| C. | 998 kHz, 999.2 kHz, 999.7 kHz, 1000.3 kHz, 1000.8 kHz and 1000.2 kHz |
| D. | none of the above |
| Answer» D. none of the above | |
| 979. |
Which one of the following is non-resonant antenna? |
| A. | Folded dipole |
| B. | Broad side array |
| C. | End fire array |
| D. | Rhombic antenna |
| Answer» E. | |
| 980. |
When the carrier is unmodulated, a certain transmitter radiates 9 kW when the carrier is sinusoidally modulated the transmitter radiates 10.125 kW. The modulation index will be |
| A. | 0.1 |
| B. | 10.15 |
| C. | 0.4 |
| D. | 0.5 |
| Answer» E. | |
| 981. |
Consider the following statements as regards advantages of CCD sensors as camera pick up tube High sensitivityGood spectral responseImage lag absent Out of the above which are correct |
| A. | 1, 2, 3 |
| B. | 1, and 2 only |
| C. | 1 and 3 only |
| D. | 2 and 3 only |
| Answer» B. 1, and 2 only | |
| 982. |
In colour TV system the colour sub carrier frequency is 4.43 MHz. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 983. |
In orthogonal BFSK, the energy of information bearing term is |
| A. | the same as total transmitted energy |
| B. | one-half of total transmitted energy |
| C. | one-fourth of total transmitted energy |
| D. | none of the above |
| Answer» C. one-fourth of total transmitted energy | |
| 984. |
As per Hartley law |
| A. | redundancy is essential |
| B. | it is necessary to use only binary codes |
| C. | maximum rate of information transmission depends on the channel bandwidth |
| D. | the maximum rate of information depends on depth of modulation |
| Answer» D. the maximum rate of information depends on depth of modulation | |
| 985. |
Which one is Analog Continuous modulation technique? |
| A. | AM |
| B. | DM |
| C. | PAM |
| D. | PCM |
| Answer» B. DM | |
| 986. |
In a hi-fi system the nonlinear distortion should be less than |
| A. | 0.1 |
| B. | 0.05 |
| C. | 0.02 |
| D. | 0.01 |
| Answer» E. | |
| 987. |
In TV system in India IF video and IF audio frequencies are |
| A. | 33.4 and 28.4 MHz respectively |
| B. | 38.9 and 33.4 MHz respectively |
| C. | 43.8 and 38.9 MHz respectively |
| D. | 33.4 and 38.9 MHz respectively |
| Answer» C. 43.8 and 38.9 MHz respectively | |
| 988. |
Assertion (A): RF tuner is called front end of TV receiverReason (R): RF tuner receives the TV signal and selects the required channel. |
| 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 | |
| 989. |
In AM, the modulation envelope has a peak value double the unmodulated carrier level, when the modulation is |
| A. | 0.25 |
| B. | 0.33 |
| C. | 0.5 |
| D. | 1 |
| Answer» E. | |
| 990. |
Tropospheric scatter is used with frequencies in the range of |
| A. | VLF |
| B. | HF |
| C. | UHF |
| D. | VHF |
| Answer» C. UHF | |
| 991. |
A pre-emphasis circuit provides extra noise immunity by |
| A. | converting the phase modulation of FM |
| B. | preamplifying the whole audio band |
| C. | amplifying the higher audio frequencies |
| D. | boosting the pass frequencies |
| Answer» D. boosting the pass frequencies | |
| 992. |
Companding is used |
| A. | to overcome quantising noise in PCM |
| B. | in PWM receivers to reduce impulse noise |
| C. | to protect small signals in PCM from quantising noise |
| D. | none of the above |
| Answer» C. to protect small signals in PCM from quantising noise | |
| 993. |
The colour of an object is decided by |
| A. | the reflected colour |
| B. | the wavelength transmitted through it |
| C. | reflected colour for opaque object and wavelength transmitted through it for transparent objects |
| D. | none of the above |
| Answer» D. none of the above | |
| 994. |
Audio tapes have two tracks each 2.5 mm wide. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 995. |
The commonly employed filter in SSB generation is |
| A. | high pass filter |
| B. | RC filter |
| C. | LC filter |
| D. | mechanical filter |
| Answer» E. | |
| 996. |
In PCM, the quantization noise depends on |
| A. | sampling rate |
| B. | signal power |
| C. | number of quantization level |
| D. | signal energy |
| Answer» D. signal energy | |
| 997. |
In a CD, the depth and width of each pit is |
| A. | 0.5 μm each |
| B. | 0.5 μm and 1 mm respectively |
| C. | 1 μm and 0.5 mm respectively |
| D. | 1 μm each |
| Answer» D. 1 Œºm each | |
| 998. |
In case of probability of the message is 1 to 16 then the information will be |
| A. | 16 bits |
| B. | 8 bits |
| C. | 4 bits |
| D. | 2 bits |
| Answer» D. 2 bits | |
| 999. |
SSB can be generated by |
| A. | filter method |
| B. | phase shift method |
| C. | weaver's method |
| D. | none of the above |
| Answer» E. | |
| 1000. |
The use of SSB |
| A. | halves the bandwidth required for transmission |
| B. | does not affect the bandwidth for transmission |
| C. | decreases the bandwidth required for transmission by 25% |
| D. | decreases the bandwidth required for transmission by 66.6% |
| Answer» B. does not affect the bandwidth for transmission | |