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64 Cards in this Set
- Front
- Back
30.(414) What describes an advantage of using fiber optic cable?
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Electromagnetic fields fo not affect fiber optic cables
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31.(414) The designation of one-millionth of a meter is
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micron
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32.(415) Most fiber optic links use infrared light that has a frequency range of about
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750 to 1500 nm.
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33.(415) What two important facts must be considered when light is propagated through a prism or a fiber?
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The refractive index and angle at whcih the light strikes the junction
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34.(415) A knowledge of the principles of refraction includes the normal,angle of refraction and
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angle of incidence
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35.(415) Propagation of light as seen by snells law is known as
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total internal reflection
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36.(415) How is attenuation measured in fiber optics?
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decibels per kilometer
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37.(415) The two main causes of attenuation in an optic fiber result from absorption and
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rayleigh scattering
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38.(416) The most useful way to classify optic fiber cables is by
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refractive indes profile and number of modes
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39.(416) In fiber optics a "mode" can best be described as
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the path light travels down a fiber
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40.(416) Which classification type of fiber optical cable has the highest dispersion throughout its length?
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Multimode step-index
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41.(416) A fiber optic cable in which the core has numerous concentric layers of glass is classified as
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multimode graded-index
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42.(417) What type of buffer allows the fiber optic cable to be twisted or pulled with little stress on the fiber?
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Loose tube
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43.(417) What outer jacket material used on fiber optic cables has a low resistance to sunlight and abrasion?
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polyvinyl chloride
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44.(417) The basic building block of a breakout cable is known as the
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subunit
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45.(418) What components make up a complete basic fiber optic link(exclude fiber connections)?
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Driver,source,optic fiber,detector,and an output circuit
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46.(418) Two types of light sources for fiber optic modems are light-emitting diodes and
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semiconductor laser diodes
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47.(418) What is one of the requirements a light source must have to be beneficial?
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Risetime must be fast enough to meet bandwidth requirement
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48.(418) What type of emmitter has an "etched well" created in the N-type gallium aluminum arsenide?
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Surface
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49.(418) What is the PN junction called in a light emmitting diode where photons are emanted?
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Depletion region
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50.(419) What type of current is producted by a photdetector when no light is present?
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Dark
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51.(419) The responsivity of a photodetector is dependent on the
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risetime of emitter
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52.(419) What photodetector converts one photon to one electron?
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Positive intrinsic negative
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53.(420) Which fiber optic cable configuration consists of multiber cables?
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Breakout cables
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54.(420) Which fiber optic connectors do not have a keying device?
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Sub-miniature,type A
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1.1[414]Who demonstrated principles of total internal reflection?
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John Tyndall
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1.2[414] Who showed how modulatied light could carry speech?
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Alexander Bell
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1.3[414] Who demonstrated the laser?
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Ted Namon
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1.4[414] Light amplification by the stimulated emission of radiation.
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laser
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1.5[414] Produced the 1st 20db/km fiber
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Corning Glass Works
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1.6[414] Power losses
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Attenution
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1.7[414] First city to use all fiber optics
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HI-OVIS
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1.8[414] Information-carrying frequency
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bandwidth
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1.9[414] Fiber is immune from ______ because the fiber is a dielectric
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EMI
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1.10[414] Based on multiples of 10
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Metrics
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1.11[414] One million Hertz
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Megahertz (MHz)
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1.12[414] One millionth of a meter
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millimeter
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1.13[414] One billionth of a meter
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Nanometer
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1.14[414] Impossible to tap
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Security
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1.15[414] Protection against fragments of silica
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Eye protection
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1.16[414] one thousandth of a meter
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Micron
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1.[415] Photon particles are a part of what spectrum?
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electromagnetic spectrum
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2.[415] What characteristic of the carrier wave does the energy possessed by the photon determine?
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the frequency
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3.[415] What si teh frequency range of infrared light?
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750 to 1,500 nm
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4.[415] As light penetrates a prism, what 2 considerations must be studied in the theory of light propagation?
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the refractive index and the angle at which light strikes the junction of the material
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5.[415] describe refractive index
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its the ratio of the speed of light in a vacuum to its speed in a given medium
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6.[415] What are the three basic facts to consider in understanding refraction?
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the normal(imaganary line perpendicular to the interface of the 2 materials), the angle of incidence (between the normal and he incident ray), and teh angle of refraction (between the refracted ray and the normal in the second material)
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7.[415] What happens to light when it passes from a higher-index material to a lower one?
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It is bent away from the normal
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8.[415]What does Snell's law state?
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If a ray of light impedes a junction of two media of different refractive indices beyond he critical angle, the light will be totally internally reflected.
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9.[415] Describe numerical aperture.
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Its a fiber's light-gathering capability
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10.[415] How is light affected in a cable that has a large numerical aperture?
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Disperion is increased
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11.[415] How does a fiber reach equilibrium-mode distribution?
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over distance
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12.[415] How is power expressed a fiber optic link?
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Microwatts and milliwatts
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13.[415] What attributes to fiber-to-fiber connection power losses?
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Acceptance cone/ejection cone mismatches, fiber core diameter mismatches, connector insertion loss, and intrinsic fiber loss
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14.[415] What unit of measurement is used for fiber optic attenuation?
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Decibles per kilometer(db/km)
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15.[415] What are the 2 main causes of attenuation in optical fibers?
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Absorption and Rayleigh scattering
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16.[415] What is spectral attenuation?
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It is related to light wavelenths and requires careful balancing of light sources and fibers.
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17.[415] How can you reduce Fresnel losses in a fiber?
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use index-matching fluids
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18.[415] What does nuclear radiation cause in fiber optic cables?
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attenuation is increaes by absorption and scattering
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19.[415] What happens when a fiber's bending radius is exceeded?
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Macrobends and microbends
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20.[415] What is disperison in a fiber optic cable?
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the spreading out of light in a fiber
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21.[415] How does disperion affect the bandwidth?
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it limits the bandwidth
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22.[415] What causes each of the two main types of disperions?
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Modal dispersion is caused by the different paths of light in varous modes, and material dispersion results from different velocities of different wavelenths
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23.[415]How is dispersion measured?
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Nanoseconds per kilometer
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