Description : In single mode operation, the value of the normalized frequency (V) should remain near the 2.405 level. If the value of V is less than 1, do single mode fibers carry a majority of the power in the core or cladding material?
Last Answer : Cladding material.
Description : The value of the normalized frequency parameter (V) relates the core size with mode propagation. When single mode fibers propagate only the fundamental mode, what is the value of V?
Last Answer : V≤2.405.
Description : The fiber's normalized frequency (V) determines how many modes a fiber can support. As the value of V increases, will the number of modes supported by the fiber increase or decrease?
Last Answer : Increase.
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 two basic types of single mode step-index fibers?
Last Answer : Matched-clad and depressed-clad.
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 : 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 : 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 : The cutoff wavelength of matched-clad and depressed-clad single mode fibers varies according to the fiber's radius of curvature and length. The cutoff wavelength of which single mode fiber type is more sensitive to length
Last Answer : Depressed-clad.
Description : A mode filter is a device that attenuates specific modes propagating in the core of an optical fiber. What mode propagating along single mode fibers do mode filters eliminate?
Last Answer : Second-order mode.
Description : What characteristic of a carrier wave is varied in frequency modulation?
Last Answer : Instantaneous frequency.
Description : The term single mode and multimode are best described as ∙ A. a number of fibers placed into 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
Last Answer : C. the number of wavelengths each fiber can support
Description : An AC circuit has capacitance arranged in series. If the line voltage remains constant, the capacitive reactance value can be varied by changing the _____________. A. line frequency B. resistance C. number of commutating poles D. number of interpoles
Last Answer : Answer: A
Description : Will the cutoff wavelength of uncabled fibers (lcf) generally have a value higher or lower than the cutoff wavelength of cabled fibers (λcc)?
Last Answer : Higher.
Description : Optical fibers or cables should never be bent at a radius of curvature smaller than a certain value. Identify this radius of curvature
Last Answer : Minimum bend radius.
Description : How can field strength be varied in a practical dc generator?
Last Answer : By varying the input voltage to the field coils
Description : What characteristic of a transistor is varied in a semiconductor-reactance modulator?
Last Answer : Collector-to-emitter capacitance.
Description : The speed of a synchronous motor is varied by _____________. A. interchanging any two of the three live leads B. changing the voltage of the system C. changing the input frequency D. increasing the field excitation
Last Answer : Answer: C
Description : In________, the phase of thecarrier is varied to represent two or more different signal elements. Both peak amplitude and frequency remain constant. A) ASK B) PSK C) FSK D) QAM
Last Answer : PSK
Description : The speed of a squirrel-cage, multi-speed, induction motor, as used aboard ship, is varied by changing the __________. A. number of connected poles in the stator B. frequency to the motor C. excitation voltage D. resistance of the rotor circuit
Description : The speed of a three-phase squirrel-cage induction-type motor operating in a fixed frequency system is varied by changing the _____________. A. number of phases to the motor B. number of stator poles C. locked rotor current D. resistance of the rotor winding
Last Answer : Answer: B
Description : How output frequency is varied in case of a thyristor?
Last Answer : The output frequency is varied by varying the turn off time of the thyristors in the inverter circuit, i.e. the delay angle of the thyristors is varied.
Description : In________, the amplitude of the carrier signal is varied to create signal elements. Both frequency and phase remainconstant. A) ASK B) PSK C) FSK D) QAM
Last Answer : ASK
Description : What is the impedance of a crystal at its resonant frequency when it is used in the series mode?
Last Answer : Minimum.
Description : What is the impedance of a crystal at its resonant frequency when it is used in the parallel mode?
Last Answer : Maximum
Description : What limits the tuning range around the center frequency of a reflex klystron in a particular mode of operation?
Last Answer : The half-power points of the mode.
Description : Which type of fiber optic connector (butt-jointed or expanded beam) brings the prepared ends of two optical fibers into close contact?
Last Answer : Butt-jointed connectors.
Description : When the axes of two connected fibers are no longer in parallel, the two connected fibers are in what kind of misalignment?
Last Answer : Angular misalignment.
Description : Silica (pure glass) fibers are used because of their low intrinsic material absorption at the wavelengths of operation. This wavelength of operation is between two intrinsic absorption regions. What are these two regions called? What are the wavelengths of operation for these two regions?
Last Answer : Ultraviolet absorption region (below 400 nm) and infrared absorption region (above 2000 nm).
Description : What are the two basic types of optical fibers?
Last Answer : Multimode and single mode fibers.
Description : Which type of optical splitter (Y-coupler or T-coupler) splits only a small amount of power from the input fiber to one of the output fibers?
Last Answer : T-coupler
Description : What is the basic fiber cleaving technique for preparing optical fibers for coupling?
Last Answer : Score-and-break.
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 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 : 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 : What five characteristics do applications using plastic clad silica (PCS) and all-plastic fibers typically have?
Last Answer : High NA, low bandwidth, tight bend radius, short length, and low cost.
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 : 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 : 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 : 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 : 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 : Will an optical fiber's attenuation coefficient vary with changes in wavelength?
Last Answer : Yes.
Description : Which dispersion mechanism (material or waveguide) is a function of the size of the fiber's core relative to the wavelength of operation?
Last Answer : Waveguide dispersion.
Description : How can loss be reduced during construction (or fabrication) of optical fibers?
Last Answer : By removing the impurities from optical fiber.
Description : You are treating a patient of deep vein thrombosis with warfarin. What value of International normalized ratio (INR) will you attempt by adjusting dose of the anticoagulant for an adequate therapeutic effect: A. 1.2 – 1.5 B. 1.3 – 1.7 C. 1.5 – 2.0 D. 2.0 – 3.0
Last Answer : D. 2.0 – 3.0
Description : What happens to the fundamental mode as the operating wavelength becomes longer than the single mode cutoff wavelength?
Last Answer : The fundamental mode becomes increasingly lossy.
Description : Will fiber coupling loss generally increase or decrease if the mode field diameter of a single mode fiber is decreased?
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