MCQOPTIONS
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MCQOPTIONS
This section includes 18 Mcqs, each offering curated multiple-choice questions to sharpen your NTPC (Technical Ability) knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
The total power content of an AM wave is 900 W. For 100% modulation, the power transmitted by each side band is |
| A. | 50 W |
| B. | 100 W |
| C. | ? 0.03 A |
| D. | 200 W |
| Answer» D. 200 W | |
| 2. |
A photodetector is made from a semiconductor In 0.53Ga 0.47As with Eg = 0.73 eV. What is the maximum wavelength, which it can detect |
| A. | 1000 nm |
| B. | 1703 nm |
| C. | \[2r+4R\] |
| D. | 173 nm |
| Answer» C. \[2r+4R\] | |
| 3. |
Consider an optical communication system operating at l~800 nm. Suppose, only 1% of the optical source frequency is the available channel bandwidth for optical communication. How many channels can be accommodated for transmitting audio signals requiring a bandwidth of 8 kHz |
| A. | 4.8 ´ 108 |
| B. | 48 |
| C. | 6 W |
| D. | 4.8 ´ 105 |
| Answer» B. 48 | |
| 4. |
The bit rate for a signal, which has a sampling rate of 8 kHz and where 16 quantisation levels have been used is |
| A. | 32000 bits/sec |
| B. | 16000 bits/sec |
| C. | \[55\,\,\mu V\] |
| D. | 72000 bits/sec |
| Answer» B. 16000 bits/sec | |
| 5. |
Range of frequencies allotted for commercial FM radio broadcast is [MNR 1997] |
| A. | 88 to 108 MHz |
| B. | 88 to 108 kHz |
| C. | 10 mA range with \[1\,\Omega \] resistance in parallel |
| D. | 88 to 108 GHz |
| Answer» B. 88 to 108 kHz | |
| 6. |
The characteristic impedance of a coaxial cable is of the order of [CPMT 2003] |
| A. | 50 W |
| B. | 200 W |
| C. | Increases by 37.5% |
| D. | None of these |
| Answer» D. None of these | |
| 7. |
When the modulating frequency is doubled, the modulation index is halved and the modulating voltage remains constant, the modulation system is |
| A. | Amplitude modulation |
| B. | Phase modulation |
| C. | \[\frac{{{r}_{1}}+{{r}_{2}}}{2}\] |
| D. | All of the above |
| Answer» D. All of the above | |
| 8. |
Sinusoidal carrier voltage of frequency 1.5 MHz and amplitude 50 V is amplitude modulated by sinusoidal voltage of frequency 10 kHz producing 50% modulation. The lower and upper side-band frequencies in kHz are |
| A. | 1490, 1510 |
| B. | 1510, 1490 |
| C. | \[\frac{{{\alpha }_{1}}{{R}_{1}}+{{\alpha }_{2}}{{R}_{2}}}{{{R}_{1}}+{{R}_{2}}}\] |
| D. | \[\frac{1}{1510},\frac{1}{1490}\] |
| Answer» B. 1510, 1490 | |
| 9. |
A laser beam is used for carrying out surgery because it [AIIMS 2003] |
| A. | Is highly monochromatic |
| B. | Is highly coherent |
| C. | \[6.56\,g/s\] |
| D. | Can be sharply focussed |
| Answer» E. | |
| 10. |
Broadcasting antennas are generally [AFMC 2003] |
| A. | Omnidirectional type |
| B. | Vertical type |
| C. | Potassium cyanide |
| D. | None of these |
| Answer» C. Potassium cyanide | |
| 11. |
Assertion : The television broadcasting becomes weaker with increasing distance. Reason : The power transmitted from TV transmitter varies inversely as the distance of the receiver |
| 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. | 9.65 A |
| D. | If the assertion and reason both are false. |
| E. | If assertion is false but reason is true. |
| Answer» D. If the assertion and reason both are false. | |
| 12. |
Assertion : In high latitude one sees colourful curtains of light hanging down from high altitudes. Reason : The high energy charged particles from the sun are deflected to polar regions by the magnetic field of the earth. [AIIMS 2003] |
| 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. | The amount of charge passed through electrolyte |
| D. | If the assertion and reason both are false. |
| E. | If assertion is false but reason is true. |
| Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion. | |
| 13. |
The linearity of a TV receiver can be checked by |
| A. | multiplier |
| B. | vector gram |
| C. | \[\pm 2%\] |
| D. | none of the above |
| Answer» C. \[\pm 2%\] | |
| 14. |
Scatter transmission is used at frequencies |
| A. | Very low frequency (VLF) |
| B. | Ultra high frequency (UHF) |
| C. | adjusting the position of braking magnet and moving it closer from the centre of the disc |
| D. | Both [b] and [c] |
| Answer» E. | |
| 15. |
The demodulation of sound signals in a TV receiver is accomplished by |
| A. | envelope detector |
| B. | discriminator |
| C. | linearity |
| D. | none of the above |
| Answer» C. linearity | |
| 16. |
The number of frames per second in TV system in India is |
| A. | 25 |
| B. | 80 |
| C. | both [a] and [b] |
| D. | 75 |
| Answer» B. 80 | |
| 17. |
Which of the following are secondary colours? |
| A. | All colours other than green, blue and red |
| B. | Green, blue and red |
| C. | loose terminal connections |
| D. | None of the above |
| Answer» B. Green, blue and red | |
| 18. |
For 51 cm size TV the voltage required for picture tube is the order of |
| A. | 13 kV |
| B. | 15 kV |
| C. | Less and thick |
| D. | 25 kV |
| Answer» C. Less and thick | |