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