MCQOPTIONS
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MCQOPTIONS
This section includes 271 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics and Telecommunication Engineering [ENT knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
What is needed to predict the performance characteristicsics of single mode fibers? |
| A. | the intermodal delay effect |
| B. | geometric distribution of light in a propagating mode |
| C. | fractional power flow in the cladding of fiber |
| D. | normalized frequency |
| Answer» C. fractional power flow in the cladding of fiber | |
| 152. |
An optical fiber has a core radius 2μmand a numerical aperture of 0.1. Will this fiber operate at single mode at 600 nm? |
| A. | yes |
| B. | no |
| Answer» B. no | |
| 153. |
A single mode fiber has mode field diameter 10.2μmand V=2.20. What is the core diameter of this fiber? |
| A. | 11.1μm |
| B. | 13.2μm |
| C. | 7.6μm |
| D. | 10.1μm |
| Answer» E. | |
| 154. |
A single mode fiber has a beat length of 4cm at 1200nm. What is birefringence? |
| A. | 2*10-5 |
| B. | 1.2*10-5 |
| C. | 3*10-5 |
| D. | 2 |
| Answer» D. 2 | |
| 155. |
Numerical aperture is constant in case of step index fiber. State whether the statement is true or false. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 156. |
Plastic fibers are less widely used than glass fibers. State whether the statement is true or false. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 157. |
Which equations are best suited for the study of electromagnetic wave propagation? |
| A. | maxwell’s equations |
| B. | allen-cahn equations |
| C. | avrami equations |
| D. | boltzmann’s equations |
| Answer» B. allen-cahn equations | |
| 158. |
When λ is optical wavelength in vacuum, k is given by k=2Π/λ. What does k stand for in the above equation? |
| A. | phase propagation constant |
| B. | dielectric constant |
| C. | boltzmann’s constant |
| D. | free-space constant |
| Answer» B. dielectric constant | |
| 159. |
Constructive interference occurs when total phase change after two successive reflections at upper and lower interfaces is equal to? (Where m is integer) |
| A. | 2Î m |
| B. | Î m |
| C. | Î m/4 |
| D. | Î m/6 |
| Answer» B. Î m | |
| 160. |
. When light is described as an electromagnetic wave, it consists of a periodically varying electric E and magnetic field H which are oriented at an angle |
| A. | 90 degree to each other |
| B. | less than 90 degree |
| C. | greater than 90 degree |
| D. | 180 degree apart |
| Answer» B. less than 90 degree | |
| 161. |
A monochromatic wave propagates along a waveguide in z direction. These points of constant phase travel in constant phase travel at a phase velocity Vp is given by |
| A. | vp=ω/β |
| B. | vp=ω/c |
| C. | vp=c/n |
| D. | vp=mass/acceleration |
| Answer» B. vp=ω/c | |
| 162. |
A most important velocity in the study of transmission characteristics of optical fiber is |
| A. | phase velocity |
| B. | group velocity |
| C. | normalized velocity |
| D. | average velocity |
| Answer» C. normalized velocity | |
| 163. |
One of the given statements is true for intermodal dispersion. Choose the right one. |
| A. | low in single mode and considerable in multimode fiber |
| B. | low in both single mode and multimode fiber |
| C. | high in both single mode and multimode fiber |
| D. | high in single mode and low in multimode fiber |
| Answer» B. low in both single mode and multimode fiber | |
| 164. |
Meridional rays in graded index fibers follow |
| A. | straight path along the axis |
| B. | curved path along the axis |
| C. | path where rays changes angles at core-cladding interface |
| D. | helical path |
| Answer» C. path where rays changes angles at core-cladding interface | |
| 165. |
What is the unit of normalized frequency? |
| A. | hertz |
| B. | meter/sec |
| C. | coulombs |
| D. | it is a dimensionless quantity |
| Answer» E. | |
| 166. |
 Which of the following statements best explain the concept of material absorption? |
| A. | a loss mechanism related to the material composition and fabrication of fiber. |
| B. | a transmission loss for optical fibers. |
| C. | results in attenuation of transmitted light. |
| D. | causes of transfer of optical power |
| Answer» B. a transmission loss for optical fibers. | |
| 167. |
A multimode step index fiber has source of RMS spectral width of 60nm and dispersion parameter for fiber is 150psnm-1km-1. Estimate rms pulse broadening due to material dispersion. |
| A. | 12.5ns km-1 |
| B. | 9.6ns km-1 |
| C. | 9.0ns km-1 |
| D. | 10.2ns km-1 |
| Answer» D. 10.2ns km-1 | |
| 168. |
Γg= dβ / C*dk. What is β in the given equation? |
| A. | attenuation constant |
| B. | propagation constant |
| C. | boltzmann’s constant |
| D. | free-space |
| Answer» C. boltzmann’s constant | |
| 169. |
For suitable power confinement of fundamental mode, the normalized frequency v should be maintained in the range 1.5 to 2.4μm 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- |
| A. | increasing level of silica doping in fiber core |
| B. | increasing level of germanium doping in fiber core |
| C. | decreasing level of silica germanium in fiber core |
| D. | decreasing level of silica doping in fiber core |
| Answer» C. decreasing level of silica germanium in fiber core | |
| 170. |
Any amount of stress occurring at the core-cladding interface would be reduced by grading the material composition. State whether the given statement is true or false. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 171. |
The variant of non-zero-dispersion-shifted fiber is called as |
| A. | dispersion flattened fiber |
| B. | zero-dispersion fiber |
| C. | positive-dispersion fiber |
| D. | negative-dispersion fiber |
| Answer» E. | |
| 172. |
Rayleigh scattering and Mie scattering are the types of |
| A. | linear scattering losses |
| B. | non-linear scattering losses |
| C. | fiber bends losses |
| D. | splicing losses |
| Answer» B. non-linear scattering losses | |
| 173. |
Dominant intrinsic loss mechanism in low absorption window between ultraviolet and infrared absorption tails is |
| A. | mie scattering |
| B. | rayleigh scattering |
| C. | stimulated raman scattering |
| D. | stimulated brillouin scattering |
| Answer» C. stimulated raman scattering | |
| 174. |
Rayleigh scattering can be reduced by operating at smallest possible wavelengths. State whether the following statement is true or false. |
| A. | true |
| B. | false |
| Answer» C. | |
| 175. |
The scattering resulting from fiber imperfections like core-cladding RI differences, diameter fluctuations, strains, and bubbles is |
| A. | rayleigh scattering |
| B. | mie scattering |
| C. | stimulated brillouin scattering |
| D. | stimulated raman scattering |
| Answer» C. stimulated brillouin scattering | |
| 176. |
Mie scattering has in-homogeneities mainly in |
| A. | forward direction |
| B. | backward direction |
| C. | all direction |
| D. | core-cladding interface |
| Answer» B. backward direction | |
| 177. |
The in-homogeneities in Mie scattering can be reduced by coating of a fiber. State whether the following statement is true or false. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 178. |
Raman and Brillouin scattering are usually observed at |
| A. | low optical power densities |
| B. | medium optical power densities |
| C. | high optical power densities |
| D. | threshold power densities |
| Answer» D. threshold power densities | |
| 179. |
The phonon is a quantum of an elastic wave in a crystal lattice. State whether the given statement is true or false. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 180. |
0.4 dB/km, 1.4μm, 6μm, 550MHz. Find threshold optical power for stimulated Raman scattering. |
| A. | 1.98 w |
| B. | 1.20 w |
| C. | 1.18 w |
| D. | 0.96 w |
| Answer» D. 0.96 w | |
| 181. |
Stimulated Brillouin scattering is mainly a |
| A. | forward process |
| B. | backward process |
| C. | upward process |
| D. | downward process |
| Answer» C. upward process | |
| 182. |
The optical source used for detection of optical signal is |
| A. | ir sensors |
| B. | photodiodes |
| C. | zener diodes |
| D. | transistors |
| Answer» C. zener diodes | |
| 183. |
High frequency optical phonon is generated in stimulated Raman scattering. State true or false |
| A. | false |
| B. | true |
| Answer» C. | |
| 184. |
What is dispersion in optical fiber communication? |
| A. | compression of light pulses |
| B. | broadening of transmitted light pulses along the channel |
| C. | overlapping of light pulses on compression |
| D. | absorption of light pulses |
| Answer» C. overlapping of light pulses on compression | |
| 185. |
When two components are equally excited at the fiber input, then for polarization maintaining fibers δΓgshould be around |
| A. | 1.5ns/km |
| B. | 1 ns/km |
| C. | 1.2ns/km |
| D. | 2ns/km |
| Answer» C. 1.2ns/km | |
| 186. |
Polarization modal noise can _________ the performance of communication system. |
| A. | degrade |
| B. | improve |
| C. | reduce |
| D. | attenuate |
| Answer» B. improve | |
| 187. |
For no overlapping of light pulses down on an optical fiber link, the digital bit rate BT must be: |
| A. | less than the reciprocal of broadened pulse duration |
| B. | more than the reciprocal of broadened pulse duration |
| C. | same as that of than the reciprocal of broadened pulse duration |
| D. | negligible |
| Answer» B. more than the reciprocal of broadened pulse duration | |
| 188. |
What does ISI stands for in optical fiber communication? |
| A. | invisible size interference |
| B. | infrared size interference |
| C. | inter-symbol interference |
| D. | inter-shape interference |
| Answer» D. inter-shape interference | |
| 189. |
The maximum bit rate that may be obtained on an optical fiber link is 1/3Γ. State whether the given statement is true or false. |
| A. | true |
| B. | false |
| Answer» C. | |
| 190. |
3dB optical bandwidth is always ___________ the 3dB electrical bandwidth. |
| A. | smaller than |
| B. | larger than |
| C. | negligible than |
| D. | equal to |
| Answer» C. negligible than | |
| 191. |
What is pulse dispersion per unit length if for a graded index fiber, 0.1μs pulse broadening is seen over a distance of 13 km? |
| A. | 6.12ns/km |
| B. | 7.69ns/km |
| C. | 10.29ns/km |
| D. | 8.23ns/km |
| Answer» C. 10.29ns/km | |
| 192. |
Chromatic dispersion is also called as intermodal dispersion. State whether the given statement true or false. |
| A. | true |
| B. | false |
| Answer» C. | |
| 193. |
 Intermodal dispersion occurring in a large amount in multimode step index fiber results in |
| A. | Â propagation of the fiber |
| B. | propagating through the fiber |
| C. | pulse broadening at output |
| D. | attenuation of waves |
| Answer» D. attenuation of waves | |
| 194. |
Chromatic dispersion is also called as intermodal dispersion. State true or false |
| A. | true |
| B. | false |
| Answer» C. | |
| 195. |
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. |
| A. | 18.23ns/km |
| B. | 20.15ns/km |
| C. | 26.93ns/km |
| D. | 10.23ns/km |
| Answer» C. 26.93ns/km | |
| 196. |
The differential attenuation of modes reduces intermodal pulse broadening on a multimode optical link. State whether the given statement is true or false. |
| A. | true |
| B. | false |
| Answer» B. false | |
| 197. |
How many categories of nonlinear effects are seen in optical fibers? |
| A. | one |
| B. | two |
| C. | three |
| D. | four |
| Answer» C. three | |
| 198. |
The index profile of a core of multimode graded index fiber is given by- |
| A. | n (r) = n1 [1 – 2Δ(r2/a)2]1/2; r<a |
| B. | n (r) = n1 [3 – 2Δ(r2/a)2]1/2; r<a |
| C. | n (r) = n1 [5 – 2Δ(r2/a)2]1/2; r>a |
| D. | n (r) = n1 [1 – 2Δ(r2/a)2]1/2; r<a |
| Answer» E. | |
| 199. |
Practical pulse broadening value for graded index fiber lies in the range of |
| A. | 0.9 to 1.2 ns/km |
| B. | 0.2 to 1 ns/km |
| C. | 0.23 to 5 ns/km |
| D. | 0.45 to 8 ns/km |
| Answer» C. 0.23 to 5 ns/km | |
| 200. |
Which of the following is not related to Kerr effects? |
| A. | self-phase modulation |
| B. | cross-phase modulation |
| C. | four-wave mixing |
| D. | stimulated raman scattering |
| Answer» E. | |