Online Questions and Answers Topic Outline
- MCQs in Principles of Light Transmission
- MCQs in Types of Light Sources, Laser, LED
- MCQs in Light Detectors
- MCQs in Modulation and Waveform
- MCQs in System Design
- MCQs in General application
- MCQs in System Bandwidth
- MCQs in Splicing Techniques
MCQs in Fiber Optics Communications Series
Following is the list of multiple choice questions in this brand new series:
Continue Practice Exam Test Questions Part V of the Series
201. In refraction that occurs in air/glass interfaces, among the visible light, which is the bent the least?
- A. violet
- B. blue
- C. red
- D. orange
202. Ratio of the velocity of propagation of a light ray in free space to the velocity of propagation of a light ray in free space in a given material.
- A. refractive index
- B. standing wave ratio
- C. velocity factor
- D. propagation velocity
203. It is the angle at which the propagating ray strikes the interface with respect to the normal.
- A. refracted angle
- B. incident angle
- C. reflected angle
- D. critical angle
204. It is the angle formed between the propagating ray and the normal after the ray has entered the second medium.
- A. angle of incidence
- B. angle of reflection
- C. propagation angle
- D. angle of refraction
205. Between silicon and gallium arsenide, which has the greatest index of refraction?
- A. Gallium arsenide
- B. Neither of silicon nor gallium arsenide
- C. Silicon
- D. They are equal
206. A fiber-optic cable has a loss of 15 dB/km. The attenuation in a cable 1000 ft. long is
- A. 4.57 dB
- B. 9.3 dB
- C. 24 dB
- D. 49.2 dB
207. Medium 1 is a glass (n1 = 1.5) and medium 2 is an ethyl alcohol (n2 = 1.36). For an angle of incidence of 30 degrees, determine the angle of refraction.
- A. 44.5 degrees
- B. 14.56 degrees
- C. 33.47 degrees
- D. 75 degrees
208. The minimum angle of incidence at which the light ray may strike the interface of two media and result in an angle of refraction of 90 degrees or greater.
- A. optimum angle
- B. angle of refraction
- C. refracted angle
- D. critical angle
209. The higher the index number
- A. the higher the speed of light
- B. the lower the speed of light
- C. has no effect on the speed of light
- D. the shorter the wavelength propagation
210. The maximum angle in which external light rays may strike the air/glass interface and still propagate down the fiber.
- A. Acceptance cone half-angle
- B. Acceptance cone
- C. Critical angle
- D. Angle of incidence
211. It is the figure of merit used to measure the magnitude of the acceptance angle.
- A. acceptance angle
- B. numerical aperture
- C. index profile
- D. refractive index
212. The effect of a large magnitude of the numerical aperture
- A. The amount of external light the fiber will accept is greater.
- B. The amount of external light the fiber will accept is less.
- C. The amount of modal dispersion will be less.
- D. The amount of chromatic dispersion will be greater.
213. Only one path for light rays to take down the fiber
- A. Multimode
- B. Step-index
- C. Single mode
- D. Graded index
214. More than one path for light rays to take down the fiber
- A. Multimode
- B. Step-index
- C. Single mode
- D. Graded index
215. The three major groups of the optical system are
- A. the components, the data rate and the response time
- B. the source, the link and the receiver
- C. the transmitter, the cable and the receiver
- D. the source, the link and the detector
216. Infrared light has a wavelength that is
- A. less than 400 nm
- B. more than 700 nm
- C. less than 700 nm
- D. a little over 400 nm
217. 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
218. It is a graphical representation of the magnitude of the refractive index across the fiber.
- A. mode
- B. index profile
- C. numerical aperture
- D. refractive index
219. 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
220. 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
221. Results in reduction in the power of light wave as it travels down the cable.
- A. power loss
- B. absorption loss
- C. resistive loss
- D. heat loss
222. Which of the following is not a factor in cable light loss?
- A. reflection
- B. absorption
- C. scattering
- D. dispersion
223. It is analogous to power dissipation to copper cables, impurities in the fiber absorb the light and covert it to heat.
- A. power loss
- B. absorption loss
- C. resistive loss
- D. heat loss
224. It is caused by valence electrons in the silica material from which the fiber are manufactured.
- A. ion resonance absorption
- B. infrared absorption
- C. ultraviolet absorption
- D. visible light absorption
225. It is a result of photons of light that are absorbed by the atoms of the glass core molecule.
- A. ion resonance absorption
- B. infrared absorption
- C. ultraviolet absorption
- D. visible light absorption
226. It is caused by hydroxide ions in the material
- A. visible light absorption
- B. infrared absorption
- C. ultraviolet absorption
- D. ion resonance absorption
227. Which type of fiber-optic cable has the least modal dispersion?
- A. single-mode step-index
- B. multimode step-index
- C. single-mode graded-index
- D. multimode graded-index
228. For a single mode optical cable with 0.25 dB/km loss, determine the optical power 100 km from a 0.1-mW light source.
- A. -45 dBm
- B. -15 dBm
- C. -35 dBm
- D. –25 dBm
229. Light rays that are emitted simultaneously from an LED and propagated down an optical fiber do not arrive at the far end of the fiber at the same time results to
- A. intramodal dispersion
- B. pulse length dispersion
- C. modal dispersion
- D. wavelength dispersion
230. Chromatic dispersion can be eliminated by __________.
- A. using a monochromatic light source
- B. using a very small numerical aperture fiber
- C. using a graded-index fiber
- D. using a very sensitive photo detector
231. Type of bend that occurs as a result of differences in thermal contraction rates between the core and the cladding material.
- A. Macrobending
- B. Microbending
- C. Quad bending
- D. Constant-radius bending
232. These bends are caused by excessive pressure and tension and generally occur while fiber are bent during handling or installation.
- A. microbending
- B. macrobending
- C. constant-radius bending
- D. kinks
233. As light is coupled in a multiport deflective device, the power is reduced by
- A. 1.5 dB
- B. 0.1 dB
- C. 0.5 dB
- D. 0.001 dB
234. It is caused by the difference in the propagation time of light rays that take different paths down the fiber.
- A. modal dispersion
- B. microbending
- C. Rayleigh scattering
- D. chromatic dispersion
235. How can modal dispersion reduced entirely?
- A. Use a graded index fiber
- B. Use a single-mode fiber
- C. Use a monochromatic light source
- D. Use a very sensitive light detector
236. It indicates what signal frequencies can be propagated through a given distance of fiber cable.
- A. Bandwidth Distance Product
- B. Pulse width dispersion
- C. Rise time
- D. Cutoff frequency
237. 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
- D. 3 GHz
238. For an optical fiber 10 km long with a pulse spreading constant of 5 ns/km, determine the maximum digital transmission rates using Return to Zero (RZ) and Nonreturn to Zero (NRZ).
- A. 5 Mbps and 10 Mbps
- B. 10 Mbps and 5 Mbps
- C. 10 Mbps and 20 Mbps
- D. 20 Mbps and 10 Mbps
239. What is the spectral width of a standard LED?
- A. 20 to 40 nm
- B. 30 to 50 nm
- C. 10 to 30 nm
- D. 40 to 60 nm
240. What is the spectral width of an ILD?
- A. 0.1 nm to 1 nm
- B. 2 nm to 5 nm
- C. 1 nm to 3 nm
- D. 3 nm to 4 nm
241. When connector losses, splice losses and coupler losses are added, what is the limiting factor?
- A. source power
- B. fiber attenuation
- C. connector and splice loss
- D. detector sensitivity
242. A pn-junction diode emits light by spontaneous emission
- A. LED
- B. APD
- C. PIN
- D. Zener diode
243. Which type of fiber optic cable is best for very high speed data?
- A. single-mode step-index
- B. multimode step-index
- C. single-mode graded-index
- D. multimode graded-index
244. A measure of conversion efficiency of a photodetector.
- A. Efficiency
- B. Responsivity
- C. Dark current
- D. Spectral response
245. The leakage current that flows through a photodiode with no light input
- A. dark voltage
- B. dark impedance
- C. dark power
- D. dark current
246. The time it takes a light induced carrier travel across the depletion region of the semiconductor.
- A. dispersion
- B. response time
- C. irradiance
- D. transit time
247. The range of wavelength values that a given photodiode will respond.
- A. spectral response
- B. permeance
- C. dark current
- D. reluctance
248. The term responsivity as it applies to a light detector is best described as
- A. the time required for the signal to go from 10 to 90 percent of maximum amplitude
- B. the ratio of the diode output current to the input optical power
- C. the ratio of the input power to output power
- D. the ratio of output current to input current
249. The minimum optical power a light detector can receive and still produce a usable electrical output signal.
- A. light responsivity
- B. light sensitivity
- C. light collectivity
- D. illumination
250. Type of lasers that uses a mixture of helium and neon enclosed in glass tube.
- A. gas lasers
- B. solid lasers
- C. semiconductor lasers
- D. liquid lasers
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