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:
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
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