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 II of the Series
51. Which of the following is not a common application of fiber-optic cable?
- a. Computer networks
- b. Long-distance telephone systems
- c. Closed circuit TV
- d. Consumer TV
52. Total internal reflection takes place if the light ray strikes the interface at an angle with what relationship to the critical angle?
- a. Less than
- b. Grater than
- c. Equal to
- d. Zero
53. The operation of the fiber-optic cable is based on the principle of
- a. Refraction
- b. Reflection
- c. Dispersion
- d. Absorption
54. Which of the following is not a common type of fiber-optic cable?
- a. Single-mode step-index
- b. Multimode graded-index
- c. Single-mode graded-index
- d. Multimode step-index
55. Cable attenuation is usually expressed in terms of
- a. Loss per foot
- b. dB/km
- c. intensity per mile
- d. voltage drop per inch
56. Which of the cable length has the highest attenuation?
- a. 1 km
- b. 2 km
- c. 95 ft
- d. 5500 ft
57. The upper pulse rate and information carrying capacity of a cable is limited by
- a. Pulse shortening
- b. Attenuation
- c. Light leakage
- d. Modal dispersion
58. The core of a fiber optic cable is made of
- a. Air
- b. Glass
- c. Diamond
- d. Quartz
59. The core of a fiber optic is surrounded by
- a. Wire braid shield
- b. Kevlar
- c. Cladding
- d. Plastic insulation
60. The speed of light in plastic compared to the speed of light in air is
- a. Slower
- b. Faster
- c. The same
- d. Either lower or faster
61. Which of the following is not a major benefit of fiber-optic cable?
- a. Immunity from interference
- b. No electrical safety problems
- c. Excellent data security
- d. Lower cost
62. The main benefit of light-wave communications over microwaves or any other communications media is
- a. Lower cost
- b. Better security
- c. Wider bandwidth
- d. Freedom from interference
63. Which of the following is not part of the optical spectrum?
- a. Infrafed
- b. Ultraviolet
- c. Visible color
- d. X-rays
64. The wavelength of visible light extends from
- a. 0.8 to 1.0 nm
- b. 400 to 750 nm
- c. 200 to 660 nm
- d. 700 to 1200 nm
65. The speed of light is
- a. 186,000 mi/h
- b. 300 mi/h
- c. 300,000 m/s
- d. 300,000,000 m/s
66. Refraction is the
- a. Bending of light waves
- b. Reflection of light waves
- c. Distortion of light waves
- d. Diffusion of light waves
67. The ratio of speed of light in air to the speed of light in another substance is called the
- a. Speed factor
- b. Index of reflection
- c. Index of refraction
- d. Dielectric constant
68. A popular light wavelength in fiber-optic cable is
- a. 0.7 um
- b. 1.3 um
- c. 1.5 um
- d. 1.8 um
69. Which type of fiber optic cable is most widely used?
- a. Single-mode step-index
- b. Multimode step-index
- c. Single-mode graded-index
- d. Multimode graded-index
70. Which type of fiber-optic cable is the best for very high speed data?
- a. Single-mode step-index
- b. Multimode step-index
- c. Single-mode graded-index
- d. Multimode graded-index
71. Which type of fiber-optic cable has the least modal dispersion?
- a. Single mode step-index
- b. Multimode step-index
- c. Single-mode graded-index
- d. Multimode graded-index
72. Which of the following is not a factor in cable light loss?
- a. Reflection
- b. Absorption
- c. Scattering
- d. Dispersion
73. A distance of 8 km is the same as
- a. 2.5 mi
- b. 5 mi
- c. 8 mi
- d. 12.9 mi
74. A fiber-optic cable has a loss of 15 dB/km. The attenuation in a cable, 100 ft long is
- a. 4.57 dB
- b. 9.3 dB
- c. 24 dB
- d. 49.2 dB
75. Fiber-optic cables with attenuations of 1.8, 3.4, 5.9, and 18 dB are linked together. The total loss is
- a. 7.5 dB
- b. 19.8 dB
- c. 29.1 dB
- d. 650 dB
76. Which light emitter is preferred for high speed data in a fiber-optic system
- a. Incandescent
- b. LED
- c. Neon
- d. Laser
77. Most fiber-optic light sources emit light in which spectrum?
- a. Visible
- b. Infrared
- c. Ultraviolet
- d. X-ray
78. Both LEDs and ILDs operate correctly with
- a. Forward bias
- b. Reverse bias
- c. Neither A or B
- d. Either A or B
79. Single-frequency light is called
- a. Pure
- b. Intense
- c. Coherent
- d. Monochromatic
80. Laser light is very bright because it is
- a. Pure
- b. White
- c. Coherent
- d. Monochromatic
81. Which of the following is NOT a common light detector
- a. PIN photodiode
- b. Photovoltaic diode
- c. Photodiode
- d. Avalanche photodiode
82. Which of the following is the fastest light sensor
- a. PIN photodiode
- b. Photovoltaic diode
- c. Phototransistor
- d. Avalanche photodiode
83. Photodiodes operate property with
- a. Forward bias
- b. Reverse bias
- c. Neither A or B
- d. Either A or B
84. The product of the bit rate and distance of a fiber-optic system is 2 Gbits km/s. What is the maximum rate at 5 km?
- a. 100 Mbits/s
- b. 200 Mbits/s
- c. 400 Mbits/s
- d. 1000 Gbits/s
85. Which fiber-optic system is better?
- a. 3 repeaters
- b. 8 repeaters
- c. 11 repeaters
- d. 20 repeaters
86. An important requirement for successful transmission system using light
- a. Powerful, reliable light source
- b. Strong glass
- c. Reliable, high cost transmission medium
- d. Powerful regenerators
87. What is used to block light from a laser and let other light through
- a. Neutral density
- b. Color
- c. Interference
- d. Spatial
88. ________ is a light that can be coherent
- a. Spontaneous emission
- b. Monochromatic and in-phase
- c. Narrow beam divergence
- d. Monochromatic
89. Coherence of laser light is important for _________
- a. Light propagation
- b. Getting laser light to pass through air
- c. Drilling holes
- d. Holography
90. The ultrapure glass used to manufacture optical fibers is approximately ___pure
- a. 99.9 %
- b. 99.99 %
- c. 99.999 %
- d. 99.9999 %
91. In fiber optics, PCS stands for
- a. Plastic-clad-silica
- b. Polyethylene-clad-silica
- c. Personal carrier system
- d. Personal communication
92. How many longitudinal modes can fall within a laser’s gain bandwidth?
- a. 2
- b. 5
- c. 9
- d. No fixed limit, dependent on bandwidth and mode spacing
93. _________ is the result of photons of light that are absorbed by the atoms of the glass core molecules
- a. Ion resonance absorption
- b. Ultraviolet absorption
- c. Infrared absorption
- d. Absorption loss
94. In fiber optics, SCS stands for
- a. Suppressed-clad-silicon
- b. Silicon base-class-silica
- c. Silica-clad-silica
- d. Serial-clad-silicon
95. Human laser was developed by A. Javen at Bell laboratory in
- a. 1960
- b. 1962
- c. 1963
- d. 1964
96. What parameter of light detector determines the range or system length that can be achieved for a given wavelength?
- a. Transit time
- b. Spectral response
- c. Dark current
- d. Responsitivity
97. Dark current in light detectors is caused by
- a. Thermally generated carriers in the diode
- b. The absence of light input
- c. Small leakage current
- d. Its imperfection
98. What is the unit of responsitivity?
- a. Ampere/volt
- b. Ampere/watt
- c. Watt/ampere
- d. Volts/ampere
99. One of the following is not a characteristic of light detectors.
- a. Responsitivity
- b. Spectral response
- c. Transmit time
- d. Dispersion
100. What is the typical wavelength of light emitted from epitaxially grown LEDs?
- a. 840 nm
- b. 490 nm
- c. 480 nm
- d. 940 nm
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