HIGHLIGHTED-Fiber-Optics-Communications.docx

A 5 cm b 10 cm c 15 cm d 20 cm 41 which of the

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a. 5 cm b. 10 cm c. 15 cm d. 20 cm 41. Which of the following factor does not harm laser efficiency? a . Atmospheric absorption b. Excitation energy not absorbed c. Problems in depopulating the lower laser level d. Inefficiency in populating the upper laser level 42. Which of the following contributes to the broadening of laser emission bandwidth? a. Doppler shift of moving atoms and molecules b. Amplification within the laser medium c. Coherence of the laser light d. Optical pumping of the laser transition 43. The first laser emitted a. Pulses of 694 nm red light b. A continuous red beam c. Pulses of white light from a helical flash lamp d. Spontaneous emission 44. What is the stage of the sand becoming a silicon? a. Liquid b. Gas c. Molten d. Hot 45. Which of the following is used as an optical transmitter on the Fiber Optical Communications? a. APD b. LSA diode c. PIN diode d. LED 46. Which of the following is used as an optical receiver in fiber optics communications a. APD b. Tunnel diode c. Laser diode d. LED 47. The numerical aperture of a fiber if the angle of acceptance is 15 degrees, is a. 017 b. 0.26 c. 0.50 d. 0.75 48. The inner portion of the fiber cable is called a. Cladding b. Coating c. Inner conductor d. Core 49. Which type of laser is the simplest to modulate directly by changing its excitation? a. Semiconductor b. Ruby c. Helium-neon d. Neodymium-YAG 50. The laser frequency when the light has the wavelength 800 nm is a. 375 x 1012 Hz b. 475 x 1015 Hz c. 375 x 109 Hz d. 375 x 1018 Hz 51. Which of the following is not a common application of fiber-optic cable? a. Computer networks b. Long-distance telephone systems c. Closed circuit TV d. Consumer TV 52. 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. Grater than c. Equal to d. Zero 53. The operation of the fiber-optic cable is based on the principle of a. Refraction b. Reflection c. Dispersion d. Absorption 54. 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 graded-index d. Multimode step-index 55. Cable attenuation is usually expressed in terms of a. Loss per foot b. dB/km c. intensity per mile d. voltage drop per inch 56. Which of the cable length has the highest attenuation? a. 1 km
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b. 2 km c. 95 ft d. 5500 ft 57. 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 58. The core of a fiber optic cable is made of a. Air b. Glass c. Diamond d. Quartz 59. The core of a fiber optic is surrounded by a. Wire braid shield b. Kevlar c. Cladding d. Plastic insulation 60. The speed of light in plastic compared to the speed of light in air is a. Slower b. Faster
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