FIBER OPTIC COMMUNICATIONS-1
Bend loss A. a form of increased attenuation caused by bends radiating from the side of the fiber B. an intermittent decrease of transmitter power caused by the curvature of the earth's surface C. a decrease of signal strength at the receiver caused by the bends of a folded dipole in a yagi antenna D. none
A
Between silicon and gallium arsenide, which has the greatest index of refraction? A. Gallium arsenide B. neither silicon nor gallium arsenide C. silicon D. they are equal
A
Chromatic dispersion can be eliminated by A. using a monochromatic light source B. Using a very small numerical aperture fiber C. using a graded index fiber D. using a very sensitive photodetector
A
EMD is best describe by which statement A. 70 % of the core diameter and B. 70 % of the fiber diameter and 70 % of the cone of acceptance should be filled with light C. 70 % of input light should be measured at the output D. 70 % of the unwanted wavelengths should be attenuated by the fiber
A
For a light detector, responsivity is measured in A. amps per watt B. uW per amp C. mA per joule D. usec per uW
A
The reflective index number is A. a number which compares the transparency of a material with that of air B. a number assigned by the manufacturer to the fiber in question C. a number which determines the core diameter D. a term for describing core elasticity
A
The speed of light in plastic compared to the speed of light in air is A. less B. more C. the same D. zero
A
Too much overfeed whilst splicing will cause A. waisting B. a bubble being formed due to air being trapped inside the fiber C. a bulge in the fiber D. runback
A
A function of an optic isolator A. cancels reflected waves B. amplifies signal transmitted C. filters unnecessary signals D. all of these
A
A single mode cable does not suffer from A. modal dispersion B. chromatic dispersion C. waveguide dispersion D. all of the above
A
APD stands for A. avalanche photodiode B. advanced photodiode C. avalanche photo detector D. advanced photo detector
A
What is the wavelength for deep violet light? A. 500 nm B. 100 nm C. 200 nm D. 700 nm
A
When light falls in a piece of black paper, what happens to most of the light? A. it is absorbed B. it is scattered C. it is reflected D. it is refracted
A
Which of the following is not a factor in cable light loss? A. reflection B. absorption C. scattering D. dispersion
A
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
A
______ is the oscillation produced when the ILD are operated above a certain threshold current A. lasing B. photons C. pulse spreading D. dark current
A
________ is the propagation method subject to the greatest distortion A. multimode step index B. multimode graded index C. multiple single index D. single mode
A
The effect of multimode propagation caused by the rays leaving the fiber to interfere constructively and destructively as they leave the end of the fiber, this effect is called A. multimode interference B. modal delay spreading C. multimode effect D. single modal effect
B
The loss in single mode fiber optic cable due to a connector is about A. 0.02 dB B. 0.2 dB C. 1 dB D. 3 dB
B
The operation of a fiber optic cable is based on the principle of A. refraction B. reflection C dispersion D. absorption
B
The type of bend that occurs as a result of differences in thermal contraction rates between the core and the cladding A. macrobending B. microbending C. quad bending D. constant K bending
B
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
B
The wavelength of visible light extends from A. 0.8 to 1.6 um B. 400 to 750 nm C. 200 to 600 nm D. 700 to 1200 nm
B
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. greater than C. equal to D. zero
B
What does the elastic store refer to in the time division multiplex system used in fiber optic A. amplifier B. detector C. holding memory D. synchronous timer
B
A parameter of light beam that do not change quantity when it enters one medium from another A. intensity B. penetration C. frequency D. wavelength
C
As light is couple in a multipoint reflective device, the power is reduced by A. 1.5 dB B. 0.1 dB C. 0.5 dB D. 0.001 dB
C
Dispersion A. Causes the core to spread out and get wider as the pulse in transmitted along the fiber B. Results in the wavelength of the light increasing along the fiber C. is the lengthening of light pulses as they travel down the fiber D. cannot occur with a laser light source
C
Laser light is very bright because it is A. pure B. white C. coherent D. monochromatic
C
One of the following is among the types of fiber optics used in electronics communications A. step index multimode B. graded index multimode C. semi graded multimode D. single mode
C
One of the following is considered the largest source of signal power loss in the use of fiber optic as communications medium such as due to misalignment A. bending B. scattering C. connection D. absoption
C
One of the following is referred to as a major component of an optical time domain reflector A. pulse generator and vertical plate B. laser and horizontal plate C. pulse generator laser D. vertical and horizontal plate
C
One of the major limitation of a plastic fiber optic used in communication A. due to its noise B. due to its bandwidth C. due too its high losses D. due to its weight
C
Optical fibers, unlike wire media, are highly resistant to A. high frequency transmission B. low frequency transmission C. electromagnetic interference D. refraction
C
Single mode step index has a core diameter in the range of A. 100 to 1000 micrometer B. 50 to 100 micrometer C. 2 to 15 micrometer D. 5 to 20 micrometer
C
The cladding which surrounds the fiber core A. is used to reduce optical interference B. is used to protect the fiber C. acts to help guide the light in the core D. ensures that the refractive index remains constant
C
The core of a fiber optic cable is surrounded by A. wire braid shield B. kevlar C. cladding D. plastic insulation
C
The dispersion of light in fiber optic cable caused by a portion of the light energy traveling in the cladding is called A. modal dispersion B. material dispersion C. waveguide dispersion D. cable dispersion
C
The effect of multimode propagation caused the rays leaving this fiber to interfere constructively and destructively as they leave the end of the fiber, this effect is called A. multimode interference B. light dispersion C. modal delay spreading D. single modal effect
C
The main benefit of light wave communications over microwaves or any other communications media are A. lower cost B. better security C. wider bandwidth D. freedom from interference
C
The mechanical splice is best suited for A. quicker installation under ideal conditions B. minimum attenuation losses C. field service conditions D. situations in which cost of equipment is not a factor
C
The most common device used as a light detector in fiber optic communication system A. LED B. darlington phototransistor C. APDs D. PIN diode
C
The ratio of the 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. speed gain
C
The term critical angle describes A. the point at which light is refracted B. the point at which light becomes invisible C. the point at which light has gone from the refractive mode to the reflective mode D. the point at which light has crossed the boundary layers from one index to another
C
The term power budgeting refers to A. the cost of cables, connectors, equipment and installation B. the loss of power due to defective components C. the total power available minus the attenuation losses D. the comparative costs of fiber and copper installations
C
The term single mode and multimode are best describes as A. the number of fibers placed into a fiber optic cable B. the number of voice channels each fiber can support C. the number of wavelengths each fiber can support D. the index number
C
This determines the maximum data rate capability of the detector A. responsivity B. dark current C. response speed D. spectral response
C
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 grade index D. multimode step index
C
An absorption loss caused by valence electrons in the silica material from which fibers are manufactured A. modal dispersion B. infrared absoption C. ion resonance absorption D. ultraviolet absorption
D
Fiber optic connections suffer high loss due A. air gaps B. rough surfaces C. axial misalignment D. all of the above
D
Fiber optic technology is used in applications of A. LANs B. cable tv (CATV) systems C. telephone networks D. all of the above
D
The 1.55 um "window" is not yet in use with fiber optic systems because A. the attenuation is higher than at 0.85 B. the attenuation is higher that at 1.3 um C. suitable laser devices have not yet been developed D. it does not lend itself to wave
D
The _______ of a detector is the fraction of incident photons that produce a photoelectron or electron hole pair A. photon efficiency B. responsivity C. aperture D. quantum efficiency
D
The core of the optical fiber has A. a medium index of refraction B. a lower index of refraction than the cladding C. a lower index of refraction than air D. a higher index of refraction than the cladding
D
The loss(attenuation) of signal in optical fiber is due to A. scattering B. absorption C. microbending D. all of the above
D
The optical band designations include A. S B. C C. L D. all of the above
D
The time it takes a light induced carrier travel across the depletion region of the semiconductor A. dispersion B. response time C. irradiance D. transit time
D
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
D
What is the device used in fiber optic communication which consist of a receiver transmitter use to clean up and amplify digital data moving in one direction and another in possible direction? A. optics compressor B. optic retarder C. optic isolator D. optic regenerator
D
The most common light used in fiber optic links is A. infra red B. red C. violet D. ultraviolet
A
In SONET, OC-1 stands for A. Optical carrier level one B. optical coupler unidirectional C. optical channel one D. optical cable type 1
A
In an optical fiber, the inner core is ______ the cladding A. denser than B. less dense than C. the same density as D. another name for
A
In fiber optics, higher mode refers to A. cladding boundary at high angle B. backscattering electromagnetic signals C. diffracting signals D. all of these
A
It is a science of measuring light throughout the entire electromagnetic spectrum A. radiometry B. photometry C. ophthalmology D. optometry
A
Loss comparisons between fusion splices and mechanical splices are A. 1:10 B. 10:1 C. 20:1 D. 1:20
A
Most fiber optic light sources emit light in which spectrum? A. visible B. infrared C. ultraviolet D. x-ray
A
Optical fibers for telecommunications are typically about _______ mills 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
A
Referred to as a limit in reducing further the loss of signal passing through a fiber optic caused by scattering A. rayleigh effect B. manufacturing effect C. natural effect D. material effect
A
Refraction is the A. bending of light waves B. reflection of light waves C. distortion of light waves D. diffusion of light waves
A
Single mode fiber is made from A. glass B. plastic C. a and b D. none of the above
A
The following consideration is important when deciding between using a diode laser or an LED A. response time B. power levels C. temperature sensitivity D. failure characteristics
A
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
B
A quarter wavelength device made of crystalline calcite that changes polarization in the optic fiber communication A. isolator B. retarder C. polarizer D. filters
B
A single fiber can handle as many voice channel as A. a pair of copper conductors B. a 1500 pair cable C. a 500 pair cable D. a 1000 pair cable
B
An advantage of fiber optic over coaxial cable as a result of coupling signals from one to the other due to changing magnet field on one or both A. feedback B. crosstalk C. electrical hazard D. shielding
B
An optic fiber regenerator which is used in communication is consisting of a __________ to clean up and amplify digital data moving in one direction and a similar system for the opposite direction A. filter and power B. transmitting and receiver C. receiver and power D. transmitter and power
B
At what power levels does fiber optic have when used in electronic communications? A. range of over 100 watts B. range of micro to milliwatts C. range of over 50 watts D. range of milliwatts to watt
B
Fibers are single mode at a particular wavelength only when V<2.405. Under what condition, if any, will the fiber cease to be single mode? A. when the wavelength of the light is greater than the cutoff wavelength B. when the wavelength of the light is less than the cutoff wavelength C. when the core diameter is extremely small D. b and c
B
In ________ propagation, the core is varying densities A. multimode step index B. multimode graded index C. multimode single index D. single mode
B
Infrared range for fiber optics A. 400 - 700 nm B. 700 - 1200 nm C. 300 - 2000 nm D. 400 - 7000 nm
B
It is a graphical representation of the magnitude of the refractive index across the fiber A. mode B. index profile C. numerical aperture D. refractive index
B
Power above the minimum required by an optical receiver is called A. gain margin B. system margin C. excess gain D. overdrive
B
The core of a fiber optic cable is made of A. air B. glass C. diamond D. quartz
B
Which cable length has the highest attenuation A. 1 km B. 2 km C. 85 ft D. 500 ft
B
Which of the following is not a common detector A. PIN diode B. photovoltaic diode C. photodiode D. avalanche photodiode
B
Which type of fiber optic cable is the most widely used? A. single mode step index? B. multimode step index C. single mode graded index D. multimode graded index?
B
In _______ propagation, the beam of propagated light is almost horizontal, and the low density core has a small diameter compared to the cores of the other propagation modes A. multimode step index B. multiple graded index C. multimode single index D. single mode
D
In the telecommunications industry, the most commonly used fibers are A. 50 micron B. 62.5 micron C. a and b D. 125 micron
D
Insertion loss is A. caused by thermal noise that intermodulates with the signal travelling on the same medium B. a momentary disruption of signal due to power interruption C. a low level high frequency signal inserted into the original signal caused by thermal noise D. none of the choices
D
Light goes from medium A to medium B at angle of incidence of 40 degrees. The angle of refraction is 30 degrees. The speed of light in B A. is the same as that in A B. is greater that in A C. is less that in A D. may be any of these, depending on the specific medium
D
Loss due to the diffraction of light when it strikes on the irregularities formed during the manufacturing process of the fiber optics A. absorption loss B. attenuation C. bending loss D. rayleigh scattering loss
D
Losses in optical fibers can be caused by (indicate false statement) A. impurities B. microbending C. attenuation in the glass D. stepped index operation
D
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
D
Recent laser developments for fiber optic communication include A. distributed feedback (DFB) B. heterojunction C. Vertical cavity surface emitting (VCSEL) D. a and c
D
Which is an advantage of optical communication links over using transmission lines or waveguides? A. small size B. extremely wide bandwidths C. immunity too electromagnetic interference (EMI) D. all of the above
D
Which of the following cables will have the highest launch power capability A. 50/125/0.2 B. 85/125/0.275 C. 62.5/125/0.275 D. 100/140/0.3
D
Which of the following is the fastest light sensor A. PIN diode B. photovoltaic diode C. phototransistor D. avalanche photodiode
D
Which of the following refers to the bandwidth of optical fiber? A. 1 Hz to 30,000 Hz B. 1KHz to 300 KHz C. 1 MHz to 300 MHz D. 1 MHz to 500 MHz
D
Which of the following refers to the relative refractive index difference of single mode fibers? A. 0.3 to 5 percent B. 0.4 to 1.5 percent C. 0.8 to 3 percent D. 0.1 to 0.3 percent
D
Which of the following terms describes the reason that light is refracted at different angles? A. photon energy changes with wavelength B. light is refracted as a function of surface smoothness C. the angle is determined partly by a and b D. the angle determined by the index of the materials
D
