Description : Why can multimode graded-index fiber 1300-nm systems using LEDs operate over longer distances and at higher bandwidths than 850-nm systems?
Last Answer : Longer distances and higher bandwidths are possible because fiber material losses and dispersion are significantly reduced at the 1300-nm region.
Description : Which types of LEDs are the preferred optical sources for short-distance, low-data-rate fiber optic systems?
Last Answer : SLEDs and ELEDs.
Description : Light travels faster in a material with a lower refractive index. Therefore, light rays that travel a longer distance in a lower refractive index travel at a greater average velocity. What effect does this have on multimode graded-index fiber modal dispersion and bandwidth?
Last Answer : Decreases the time difference between light rays, which reduces modal dispersion and increases fiber bandwidth.
Description : Which semiconductor sources (LD or LED) emit more focused light and are capable of launching sufficient optical power into both single mode and multimode fibers?
Last Answer : LDs.
Description : Modal dispersion affects the bandwidth of multimode systems. It is essential to adjust what three fiber properties to maximize system bandwidth?
Last Answer : Core diameter, NA, and index profile properties.
Description : The graded-index multimode optical fiber has a core diameter of _____ nm. ∙ a. 0.5 ∙ b. 0.05 ∙ c. 0.0005 ∙ d. 5
Last Answer : ∙ a. 0.5
Description : A step-index multimode optical fiber has a core diameter of _____ nm. ∙ a. 0.02 ∙ b. 0.2 ∙ c. 2 ∙ d. 0.002
Last Answer : b. 0.2
Description : Does underfilling a multimode optical fiber excite mainly high-order or low-order modes?
Last Answer : Low-order modes.
Description : In the event of cabin depressurization, the actions of the pilot will be to: a. Immediately commence a diversion to a suitable alternate b. Increase engine power to provide additional ... a descent to an altitude where the supplemental oxygen supply is sufficient for all crew and passengers
Last Answer : d. Commence a descent to an altitude where the supplemental oxygen supply is sufficient for all crew and passengers
Description : A flight is planned from L to M, distance 850 nm. Wind component out is 35 kt(TWC), TAS 450kt. Mean fuel flow out is 2500kg/hr, mean fuel flow inbound is 1900kg/hr and the fuel available is 6000kg. The time ... 1hr 30 min, 660nm b. 1hr 30 min, 616nm c. 1hr 15 min, 606nm d. 1hr 16 min, 616nm
Last Answer : d. 1hr 16 min, 616nm
Description : A flight is planned from L to M, distance 850 nm. Wind component out is 35 kt(TWC), TAS 450kt. Mean fuel flow out is 2500kg/hr, mean fuel flow inbound is 1900kg/hr and the fuel available is 6000kg. The time ... 30 min, 660nm b. 1hr 30 min, 616nm c. 1hr 15 min, 606nm d. 1hr 16 min, 616nm
Description : _____uses short-wave850-nm multimode fiber. A) 10GBase-S B) 10GBase-L C) 10GBase-E D) none of the above
Last Answer : 10GBase-S
Description : Multimode optical fibers can have a step-index or graded index refractive index profile. Which fiber, multimode step-index or multimode graded-index fiber, usually performs better?
Last Answer : Multimode graded-index fiber
Description : Which type of optical fiber (multimode or single mode) tends to have lower loss and produces less signal distortion?
Last Answer : Single mode fiber.
Description : What is the typical wavelength of light emitted from epitaxially grown LEDs? ∙ a. 840 nm ∙ b. 490 nm ∙ c. 480 nm ∙ d. 940 nm
Last Answer : ∙ d. 940 nm
Description : List three benefits that properly cabled optical fibers provide.
Last Answer : a. Protect optical fibers from damage or breakage during installation and over the fiber's lifetime. b. Provide stable fiber transmission characteristics compared with uncabled fibers. c. Maintain the physical integrity of the optical fiber.
Description : Multimode step-index fibers have relatively large core diameters and large numerical apertures. These provide what benefit?
Last Answer : Make it easier to couple light from a light-emitting diode (LED) into the fiber.
Description : A major breakthrough in the studies of cells came with the development of electron microscope. This is because (a) the electron microscope is more powerful than the light microscope as it ... (d) electron beam can pass through thick materials, whereas light microscopy requires thin sections.
Last Answer : (b) the resolving power of the electron microscope is much higher than that of the light microscope
Description : Why are LEDs preferred over laser diodes for low- and moderate-frequency analog applications?
Last Answer : LEDs require less complex circuitry than lasers.
Description : How many modes possible with a multimode step-index with a core diameter of 50 um, a core refractive index of 1.6, a cladding refractive index of 1.584, and a wavelength of 1300 nm. ∙ A. 456 ∙ B. 213 ∙ C. 145 ∙ D. 372
Last Answer : D. 372
Description : List the two principal optical detectors used in fiber optic systems.
Last Answer : The semiconductor positive-intrinsic-negative (PIN) photodiode and avalanche photodiode (APD).
Description : It is an average power of a radio transmitter supplied to the antenna transmission line taken during a long sufficient interval of time and compared with the lowest frequency encountered in the modulation ... operating conditions. A. Carrier power B. Rated power C. Mean power D. Peak envelop power
Last Answer : C. Mean power
Description : List the standard core sizes for multimode step-index, multimode graded-index, and single mode fibers
Last Answer : Multimode step-index fibers: 50µm and 100µm. Multimode graded-index fibers: 50µm, 62.5µm, 85µm, and 100µm. Single mode fibers: between 8µm and 10µm.
Description : 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
Last Answer : ∙ a. It has high losses
Description : Ho w many times bigger does the bandwidth of a fiber optic multimode have over a cable? A. 50 times bigger B. 100 times bigger C. 10 times bigger D. 5 times bigger
Last Answer : B. 100 times bigger
Description : For a 300-m optical fiber cable with a bandwidth distance product of 600 MHz-km, determine the bandwidth. ∙ A. 5 GHz ∙ B. 1 GHz ∙ C. 2 GHz
Last Answer : C. 2 GHz
Description : Which performance parameter is the minimum amount of optical power required to achieve a specific bit-error rate (BER) in digital systems or a given signal-to-noise ratio (SNR) in analog systems?
Last Answer : Receiver sensitivity.
Description : Are the effects of temperature changes on LDs more or less significant than for LEDs?
Last Answer : More.
Description : Semiconductor LEDs emit incoherent light. Define incoherent light
Last Answer : Light waves that lack a fixed-phase relationship
Description : List the types of materials used in fabricating low-loss, long wavelength optical fibers.
Last Answer : Heavy-metal fluorides, chalcogenide glasses, and crystalline materials.
Description : A four-pole induction motor, operating on three-phase 60 cycle current will operate at approximately ___________. A. 850 RPM B. 1,150 RPM C. 1,750 RPM D. 3,550 RPM
Last Answer : Answer: C
Description : A type of index of an optical fiber that has no cladding and whose central core has a non-uniform refractive index. ∙ A. graded index ∙ B. multimode ∙ C. single mode ∙ D. step-index
Last Answer : ∙ A. graded index
Description : A type of index profile of an optical fiber that has a central core and outside cladding with a uniform refractive index ∙ A. multimode ∙ B. graded index ∙ C. step-index ∙ D. single mode
Last Answer : ∙ C. step-index
Description : Names of some of the Operating Systems are given below: (a) MS-DOS (b) XENIX (c) OS/2 In the above list, following operating systems didn’t provide multiuser facility. (1) (a) only (2) (a) and (b) only (3) (b) and (C) only (4) (a), (b) and (c)
Last Answer : Answer: Marks to all
Description : The width of the frequency band which is just sufficient to ensure the transmission of information at the rate and with the quality required under a specified condition and class of emission. A. Occupied bandwidth B. Reference frequency C. Necessary bandwidth D. Frequency tolerance bandwidth
Last Answer : C. Necessary bandwidth
Description : List the three techniques used by manufacturers to buffer optical fibers.
Last Answer : Tight-buffered, loose-tube, and gel-filled loose-tube.
Description : List the three parts of an optical fiber.
Last Answer : Core, cladding, and coating or buffer.
Description : Which are more sensitive to alignment errors, single mode or multimode fibers?
Last Answer : Single mode.
Description : Do small core distortions formed by arc fusion's self alignment mechanism have more of an affect on light propagating through multimode or single mode fibers?
Last Answer : Single mode fibers.
Description : What are the two methods used by fiber manufacturers to fabricate multimode and single mode glass fibers?
Last Answer : Vapor phase oxidation and direct-melt process.
Description : What are the most distinguishing characteristics of a multimode graded-index fiber?
Last Answer : Source-to-fiber coupling efficiency and insensitivity to microbending and macrobending losses.
Description : What multimode graded-index fiber offers the best overall performance for most applications?
Last Answer : 62.5/125 mm multimode graded-index fiber.
Description : What four fiber properties determine the number of modes propagating in a multimode gradedindex fiber?
Last Answer : Numerical aperture (NA), relative refractive index difference ( D), profile parameter (α), and normalized frequency (V).
Description : Light propagates in multimode graded-index fibers according to refraction and total internal reflection. When does total internal reflection occur?
Last Answer : When the angle of incidence becomes larger than the critical angle of incidence.
Description : The profile parameter (α) determines the shape of the multimode graded-index core's refractive index profile. As the value of the aincreases, how does the core's profile change?
Last Answer : From a triangular shape to step.
Description : In multimode step-index fibers, the majority of light propagates in the fiber core for what reason?
Last Answer : Most modes in multimode step-index fibers propagate far from cutoff.
Description : Multimode step-index fibers have a core and cladding of constant refractive index n1 and n2, respectively. Which refractive index, the core or cladding, is lower?
Last Answer : Cladding.
Description : in multimode fibers, how do fiber joints increase fiber attenuation following the joint?
Last Answer : By disturbing the fiber's mode power distribution (MPD).
Description : Explain the difference between multimode and single mode core-cladding concentricity errors.
Last Answer : Multimode core-cladding concentricity error is the distance between the core and cladding centers expressed as a percentage of core diameter while the single mode core-cladding concentricity error is just the distance between the core and cladding centers
Description : What two properties of the launch condition may affect multimode fiber attenuation measurements?
Last Answer : . Launch spot size and angular distribution.