MCQs in Fiber Optics Communications Part III

(Last Updated On: December 8, 2017)

MCQs in Fiber Optics Communications - Part III

This is the Multiples Choice Questions Part 3 of the Series in Fiber Optics Communications as one of the Communications Engineering topic. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Examination Questions in Electronic System and Technologies, Communications Books, Journals and other Communications References.

Online Questions and Answers Topic Outline

  • MCQs in Principles of Light Transmission
  • MCQs in Types of Light Sources, Laser, LED
  • MCQs in Light Detectors
  • MCQs in Modulation and Waveform
  • MCQs in System Design
  • MCQs in General application
  • MCQs in System Bandwidth
  • MCQs in Splicing Techniques

MCQs in Fiber Optics Communications Series

Following is the list of multiple choice questions in this brand new series:

Optical Fiber Communications MCQs
PART 1: MCQs from Number 1 – 50                        Answer key: PART I
PART 2: MCQs from Number 51 – 100                   Answer key: PART II
PART 3: MCQs from Number 101 – 150                 Answer key: PART III
PART 4: MCQs from Number 151 – 200                 Answer key: PART IV
PART 5: MCQs from Number 201 – 250                 Answer key: PART V
PART 6: MCQs from Number 251 – 300                 Answer key: PART VI

Continue Practice Exam Test Questions Part III of the Series

101. SONET stands for

  • a. System Optical Network
  • b. Synchronous Optical Network
  • c. Silica Optic Network
  • d. System Optical Fiber Net

102. Band loss is

  • a. A reduction in transmitter power caused by earth’s surface curvature
  • b. A reduction in strength of the signal caused by folded dipole bends
  • c. An attenuation increase caused by bends radiating from the side of the fiber
  • d. All of these

103. Infrared range for fiber optics

  • a. 400 – 700 nm
  • b. 700 – 1200 nm
  • c. 300 – 2000 nm
  • d. 400 – 7000 nm

104. Which of the following is a disadvantage for plastic fiber optics?

  • a. Noise immunity
  • b. Electric hazards
  • c. Higher losses
  • d. All of these

105. OTDR stands for

  • a. Optical Time Domain Reflectometer
  • b. Optical Transmit Direction Return
  • c. Optical Time Domain Time Regeneration
  • d. Overtime Direct Reference

106. Which of the following is determined by an OTDR?

  • a. Distance to trouble
  • b. Length of fiber
  • c. Refractive index
  • d. All of these

107. Under normal condition, a single fiber should not be used for a two-way communication mainly because of

  • a. Loss
  • b. Fading
  • c. Noise
  • d. Attenuation

108. A single mode optical fiber has a core diameter of _____ nm.

  • a. 0.1
  • b. 0.01
  • c. 0.2
  • d. 0.05

109. A step-index multimode optical fiber has a core diameter of _____ nm.

  • a. 0.02
  • b. 0.2
  • c. 2
  • d. 0.002

110. The graded-index multimode optical fiber has a core diameter of _____ nm.

  • a. 0.5
  • b. 0.05
  • c. 0.0005
  • d. 5

111. Which is not a possible cause of optical fiber loss?

  • a. Impurities
  • b. Glass attenuation
  • c. Stepped index operation
  • d. Microbending

112. The ratio of the speed of light in a vacuum and the speed of light in the material used.

  • a. S/N ratio
  • b. Refractive index
  • c. Intermodal dispersion
  • d. Monomode ratio

113. Splicing fibers means

  • a. Fusion
  • b. Butt
  • c. Glue
  • d. Both fusion and butt

114. An IC that represents a short distance one-way optical communications

  • a. Optoisolator
  • b. Insulator
  • c. Multivibrator
  • d. Optical IC

115. When light strikes a flat polished end of a fiber, it produces a loss of

  • a. 14 %
  • b. 4 %
  • c. 10 %
  • d. 1 %

116. When light strikes a flat polished end of a fiber, the fiber loss produced can be reduced by

  • a. Splicing
  • b. Antireflection coating
  • c. Insulation jacket
  • d. All of these

117. In fiber optics, higher-order mode refers to

  • a. Cladding boundary at high angle
  • b. Backscattering electromagnetic signals
  • c. Diffracting signals
  • d. All of these

118. The following are the cause of light attenuation in fiber optics except

  • a. Backscattering
  • b. Absorption
  • c. Refraction
  • d. Microbends

119. Why are visible-light LEDs not used for fiber optics?

  • a. It has high losses
  • b. It has short wave
  • c. It has low attenuation
  • d. It has weak signal

120. Optical cable testers are used for

  • a. Checking refractive index
  • b. Light power out of a fiber
  • c. Non-calibrated light into a fiber
  • d. Checking maximum distance covered

121. A function of an optic isolator

  • a. Cancels reflective waves
  • b. Amplifies signal transmitted
  • c. Filters unnecessary signals
  • d. All of these

122. An increase in light intensity produces fast optic switching due to

  • a. Increase in index of glass
  • b. Amplification of optical signal
  • c. High gain
  • d. Photoconductivity

123. Light traveling in optical fiber follows which of the following principles.

  • a. Huygen’s principle
  • b. Reflection theory
  • c. Light theory
  • d. Snell’s law

124. Optical fibers for telecommunications are typically about _____ mils thick and consists of a glass core, a glass cladding of lower index of refraction, and a protective coating

  • a. 5
  • b. 6
  • c. 7
  • d. 8

125. Material dispersion is caused by the

  • a. Wavelength dependence of the index of refraction
  • b. Wavelength independence of the index of refraction
  • c. Dependence of the propagation constant on the mode number
  • d. Independence of the propagation constant on the mode number

126. Modal dispersion is caused by the

  • a. Dependence of wavelength on index of refraction
  • b. Dependence of propagation constant on index of refraction
  • c. Dependence of the propagation constant on the wavelength
  • d. Dependence of the propagation constant on the mode number

127. The dominant loss mechanisms in silica fiber are

  • a. Absorption and radiation losses
  • b. Absorption and Rayleigh scattering
  • c. Coupling and radiation losses
  • d. Radiation and modal dispersion

128. The bandwidth of a fiber is limited by

  • a. Mode
  • b. Wavelength
  • c. Dispersion
  • d. Frequency

129. Fiber bandwidth is generally specified as the

  • a. Product of the bandwidth and distance
  • b. Sum of the bandwidth and distance
  • c. Difference of the bandwidth and distance
  • d. Quotient of bandwidth and distance

130. The _____ of a detector is the fraction of incident photons that produce a photoelectron or electron-hole pair

  • a. Responsitivity
  • b. Photon efficiency
  • c. Aperture
  • d. Quantum efficiency

131. In solid-state optical detectors, the excited charge is transported in the solid by

  • a. Holes and protons
  • b. Holes and electrons
  • c. Anion and cation
  • d. Protons and photons

132. One of the following is not a solid-state optical detector

  • a. APD
  • b. PIN
  • c. PMT
  • d. Phototransistors

133. Optical detectors are square-law devices because they respond to _____ rather than amplitude

  • a. Intensity
  • b. Light
  • c. Density
  • d. Photon

134. The _____ is equal to the number of electrons emitted per second times the electron charge

  • a. Intensity
  • b. Optical power
  • c. Photocurrent
  • d. Responsitivity

135. Which optical detector is used when high sensitivity and bandwidth are required?

  • a. PMT
  • b. APD
  • c. PIN
  • d. Phototransistor

136. What is the average loss in fiber splice?

  • a. 0.10 dB
  • b. 0.15 dB
  • c. 0.20 dB
  • d. 0.25 dB

137. Which of the following colors is not found in the visible light wave spectrum?

  • a. Red
  • b. White
  • c. Orange
  • d. Yellow

138. What is the frequency limit of an optical fiber?

  • a. 20 GHz
  • b. 30 GHz
  • c. 40 GHz
  • d. 50 GHz

139. The mechanical splice attenuation loss is _____ dB or less

  • a. 0.1
  • b. 0.01
  • c. 0.001
  • d. 1

140. _____ is applied to protect core and cladding of the fiber

  • a. Insulation
  • b. Fiber insulation
  • c. Silica
  • d. Polymer jacket

141. The energy of the photon is

  • a. Directly proportional to its bandwidth
  • b. Directly proportional to the Planck’s constant
  • c. Directly proportional to Boltzmann’s constant
  • d. Inversely proportional to the Planck’s constant

142. Refractive index of glass

  • a. 1.0
  • b. 1.2
  • c. 1.4
  • d. 1.5

143. Refractive index of diamond

  • a. 1.0
  • b. 1.4
  • c. 1.8
  • d. 2.0

144. What is the unit of light wavelength?

  • a. Micrometer
  • b. Angstroms
  • c. Mils
  • d. Fathom

145. How much is the power loss of the fusion splice?

  • a. 0.1 dB or less
  • b. 0.01 dB or less
  • c. 1 dB or less
  • d. 10 dB or less

146. Used to test a fiber optics splice

  • a. Spectrum analyzer
  • b. Oscilloscope
  • c. Optical power meter
  • d. Field strength meter

147. A coupler which consists of a series of lenses and a partly reflective surface

  • a. Beam-splitting coupler
  • b. Reflective star coupler
  • c. Fused coupler
  • d. None of these

148. Reflections in many directions

  • a. Diffuse reflection
  • b. Diffraction
  • c. Scattering
  • d. Dispersion

149. Commonly used electro-optic crystal for polarization modulation

  • a. Lithium Niobate
  • b. Tourmaline
  • c. Sodium Chlorate
  • d. Sphalerite

150. Which modulation methods are the most widely used in optical systems?

  • a. Phase and frequency modulations
  • b. Polarization modulation and phase modulation
  • c. Intensity modulation and phase modulation
  • d. Intensity modulation and polarization modulation

Complete List of MCQs in Communications Engineering per topic

MCQs in Fiber Optics Communications Part III
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