# Computer/Computer Networks MCQs Set-4 Sample Test,Sample questions

## Question: ``` Practical pulse broadening value for graded index fiber lies in the range of __________ ```

1.0.9 to 1.2 ns/km

2.0.2 to 1 ns/km

3.0.23 to 5 ns/km

4.0.45 to 8 ns/km

Posted Date:-2022-05-06 16:48:42

## Question: ``` _________ can potentially provide spectral conservation through the use of multilevel signalling. ```

1.M-ary PSK

2.MFSK

4.DFSK

Posted Date:-2022-05-06 17:05:40

## Question: ```A 4 km optical link consists of multimode step index fiber with core refractive index of 1.3 and a relative refractive index difference of 1%. Find the delay difference between the slowest and fastest modes at the fiber output. ```

1.0.173 Î¼sec

2.0.152 Î¼sec

3.0.96 Î¼sec

4.0.121 Î¼sec

Posted Date:-2022-05-06 16:45:43

## Question: ```A decibel may be defined as the ratio of input and output optical power for a particular optical wavelength. ```

1.True

2.False

Posted Date:-2022-05-06 16:25:54

## Question: ```A device that reduces the intensity of light in optical fiber communications is ___________ ```

1.compressor

2.Optical attenuator

3.Barometer

4.Reducer

Posted Date:-2022-05-06 16:25:06

## Question: ```A multimode fiber has RMS pulse broadening per km of 12ns/km and 28ns/km due to material dispersion and intermodal dispersion resp. Find the total RMS pulse broadening. ```

1.30.46ns/km

2.31.23ns/km

3.28.12ns/km

4.26.10ns/km

Posted Date:-2022-05-06 16:27:40

## Question: ```A multimode step-index fiber has a core refractive index of 1.5 and relative refractive index difference of 1%. The length of the optical link is 6 km. Estimate the RMS pulse broadening due to intermodal dispersion on the link. ```

1.92.6 ns

2.86.7 ns

3.69.3 ns

4.68.32 ns

Posted Date:-2022-05-06 16:46:26

## Question: ```After Total Internal Reflection the Meridional ray __________ ```

1.Makes an angle equal to acceptance angle with the axial ray

2.Makes an angle equal to critical angle with the axial ray

3.Travels parallel equal to critical angle with the axial ray

4.Makes an angle equal to critical angle with the axial ray

Posted Date:-2022-05-06 16:44:12

## Question: ```Almost _________ of the transmitter power is wasted in the use of external modulators. ```

1.Half

2.Quarter

3.One-third

4.Twice

Posted Date:-2022-05-06 17:00:41

## Question: ```An alternative modification of the dispersion characteristics of single mode fibers involves achievement of low dispersion gap over the low-loss wavelength region between __________ ```

1.0.2 and 0.9Î¼m

2.0.1 and 0.2Î¼m

3.1.3 and 1.6Î¼m

4.2 and 3Î¼m

Posted Date:-2022-05-06 16:30:24

## Question: ```An optical fiber behaves as a birefringence medium due to differences in ___________ ```

1.Effective R-I and core geometry

3.Transmission/propagation time of waves

4.Refractive indices of glass and silica

Posted Date:-2022-05-06 16:53:49

## Question: ```Beat length of a single mode optical fiber is 0.6cm. Calculate the difference between propagation constants for the orthogonal modes. ```

1.69.8

2.99.86

3.73.2

4.104.66

Posted Date:-2022-05-06 16:56:38

## Question: ```Consider a single mode fiber having core refractive index n1= 1.5. The fiber length is 12m. Find the time taken by the axial ray to travel along the fiber. ```

1.1.00Î¼sec

2.0.06Î¼sec

3.0.90Î¼sec

4.0.30Î¼sec

Posted Date:-2022-05-06 16:44:54

## Question: ```Conventional optical fibers has more transmission losses than photonic crystal fibers. ```

1.True

2.False

Posted Date:-2022-05-06 16:18:25

## Question: ```Digital transmission is more likely to be affected by modal noise. ```

1.True

2.False

Posted Date:-2022-05-06 16:51:35

## Question: ```Dispersion-shifted single mode fibers are created by __________ ```

1.Increasing fiber core diameter and decreasing fractional index difference

2.Decreasing fiber core diameter and decreasing fractional index difference

3.Decreasing fiber core diameter and increasing fractional index difference

4.Increasing fiber core diameter and increasing fractional index difference

Posted Date:-2022-05-06 16:29:36

## Question: ```Disturbance along the fiber such as vibrations, discontinuities, connectors, splices, source/detectors coupling result in __________ ```

1.Modal noise

2.Inter-symbol interference

3.Infrared interference

Posted Date:-2022-05-06 16:50:26

## Question: ```Eight level FSK and binary PSK yields an equivalent sensitivity. ```

1.False

2.True

Posted Date:-2022-05-06 17:04:27

## Question: ```Estimate RMS pulse broadening per km due to intermodal dispersion for multimode step index fiber where length of fiber is 4 km and pulse broadening per km is 80.6 ns. ```

1.18.23ns/km

2.20.15ns/km

3.26.93ns/km

4.10.23ns/km

Posted Date:-2022-05-06 16:47:56

## Question: ```External modulation for ________ modulation format allows the most sensitive coherent detection mechanism. ```

1.FSK

2. DSK

3.PSK

Posted Date:-2022-05-06 17:05:04

## Question: ```For many applications that involve optical fiber transmission, an intensity modulation optical source is not required. ```

1.True

2.False

Posted Date:-2022-05-06 16:52:10

## Question: ```For suitable power confinement of fundamental mode, the normalized frequency v should be maintained in the range 1.5 to 2.4Î¼m and the fractional index difference must be linearly increased as a square function while the core diameter is linearly reduced to keep v constant. This confinement is achieved by? ```

1.Increasing level of silica doping in fiber core

2.Increasing level of germanium doping in fiber core

3.Decreasing level of silica germanium in fiber core

4.Decreasing level of silica doping in fiber core

Posted Date:-2022-05-06 16:39:38

## Question: ```If the input power 100Î¼W is launched into 6 km of fiber, the mean optical power at the fiber output is 2Î¼W. What is the overall signal attenuation through the fiber assuming there are no connectors or splices? ```

1.15.23dB

2.16.98dB

3.17.12dB

4.16.62dB

Posted Date:-2022-05-06 16:24:18

## Question: ```In index-guided photonic crystal fiber structure, the dark areas are air holes. What does white areas suggests? ```

1.Air

2.Silica

3.Water

4.Plasma

Posted Date:-2022-05-06 16:21:55

## Question: ```Intermodal dispersion in multimode fibers is minimized with the use of step-index fibers. ```

1.True

2. False

Posted Date:-2022-05-06 16:47:16

## Question: ```Intermodal dispersion occurring in a large amount in multimode step index fiber results in ____________ ```

1.Propagation of the fiber

2.Propagating through the fiber

4.Attenuation of waves

Posted Date:-2022-05-06 16:43:28

## Question: ```Losses in photonic crystal fibers are reduced to a level of ___________ ```

1.0.1dB/km

2.0.2dB/km

3.0.3dB/km

4.0.4dB/km

Posted Date:-2022-05-06 16:19:05

## Question: ```Most of the power in an optical fiber is transmitted in fiber cladding. ```

1.True

2.False

Posted Date:-2022-05-06 16:28:19

## Question: ```Non-zero-dispersion-shifted fiber was introduced in the year 2000. ```

1.True

2.False

Posted Date:-2022-05-06 16:42:16

## Question: ```ny amount of stress occurring at the core-cladding interface would be reduced by grading the material composition. ```

1.True

2.False

Posted Date:-2022-05-06 16:40:39

## Question: ```Photonic crystal fibers also called as ___________ ```

1.Conventional fibers

2.Dotted fibers

3.Stripped fibers

4.Holey fibers

Posted Date:-2022-05-06 16:17:57

## Question: ```Polarization modal noise can _________ the performance of communication system. ```

2.Improve

3.Reduce

4.Attenuate

Posted Date:-2022-05-06 16:57:26

## Question: ```The differential attenuation of modes reduces intermodal pulse broadening on a multimode optical link. ```

1.True

2.False

Posted Date:-2022-05-06 16:46:50

## Question: ```The digital transmission on implementation of polarization modulation which involves polarization characteristics of the transmitted optical signal is known as _____________ ```

1.Frequency shift keying

2.Amplitude shift keying

3.Phase shift keying

4.Polarization shift keying

Posted Date:-2022-05-06 17:06:27

## Question: ```The fibers which relax the spectral requirements for optical sources and allow flexible wavelength division multiplying are known as __________ ```

1.Dispersion-flattened single mode fiber

2.Dispersion-enhanced single mode fiber

3.Dispersion-compressed single mode fiber

4.Dispersion-standardized single mode fiber

Posted Date:-2022-05-06 16:38:44

## Question: ```The high index contrast enables the PCF core to be reduced from around 8 Î¼min conventional fiber to ___________ ```

1.Less than 1Î¼m

2.More than 5Î¼m

3.More than 3Î¼m

4.More than 2Î¼m

Posted Date:-2022-05-06 16:20:08

## Question: ```The line width in the range ________ of bit rate is specified for ASK heterodyne detection. ```

1.8%

2.2 to 8%

3.10 t0 50%

4.70%

Posted Date:-2022-05-06 17:01:15

## Question: ```The modal noise can be reduced by __________ ```

1.Decreasing width of signal longitudinal mode

2.Increasing coherence time

3.Decreasing number of longitudinal modes

4.Using fiber with large numerical aperture

Posted Date:-2022-05-06 16:51:14

## Question: ```The modal noise occurs when uncorrected source frequency is? ```

1.Î´f>>1/Î´T

2.Î´f=1/Î´T

3.Î´f<<1/Î´T

4.Negligible

Posted Date:-2022-05-06 16:49:40

## Question: ```The optical fiber incurs a loss in signal power as light travels down the fiber which is called as ___________ ```

1.Scattering

2.Attenuation

3.Absorption

4. Refraction

Posted Date:-2022-05-06 16:23:35

## Question: ```The optical source used for detection of optical signal is ____________ ```

1.IR sensors

2.Photodiodes

3.Zener diodes

4.Transistors

Posted Date:-2022-05-06 16:53:03

## Question: ```The periodic arrangement of cladding air holes in photonic band gap fibers provides for the formation of a photonic band gap in the ___________ ```

1.H-plane of fiber

2.E-plane of fiber

3.E-H-plane of fiber

4.Transverse plane of fiber

Posted Date:-2022-05-06 16:20:53

## Question: ```The signals which are obtained by encoding each quantized signal into a digital word is called as ```

1.PAM signal

2.PCM signal

3.FM signal

4.Sampling and quantization

Posted Date:-2022-05-06 17:07:49

## Question: ```The variant of non-zero-dispersion-shifted fiber is called as __________ ```

1.Dispersion flattened fiber

2.Zero-dispersion fiber

3.Positive-dispersion fiber

4.Negative-dispersion fiber

Posted Date:-2022-05-06 16:41:33

## Question: ```When the input and output power in an optical fiber is 120Î¼W & 3Î¼W respectively and the length of the fiber is 8 km. What is the signal attenuation per km for the fiber? ```

1.3dB/km

2.2dB/km

3. 1dB/km

4.4dB/km

Posted Date:-2022-05-06 16:26:36

## Question: ```Which is the unit of measurement of attenuation in optical fibers? ```

1.km

2.dB

3.dB/km

4.Coulombâ€™s

Posted Date:-2022-05-06 16:22:52

## Question: ```________ does not require an external modulator. ```

1.FSK

2.DSK

3.PSK

Posted Date:-2022-05-06 17:02:38

## Question: ```___________ offers the potential for improving the coherent optical receiver sensitivity by increasing the choice of signalling frequencies. ```

1.MFSK

2.MDSK

3.MPSK

Posted Date:-2022-05-06 17:03:31

## Question: ```_____________ is essentially a crude form of Amplitude shift keying. ```

1.Analog modulation

2.Digital intensity modulation

3.Photodetector

Posted Date:-2022-05-06 16:59:04

1.FSK

2.DSK

3.PSK