Description : Luminance efficiency is minimum for a a. Fluorescent tube b. High wattage light bulb c. Mercury vapor lamp d. Low wattage light bulb
Last Answer : d. Low wattage light bulb
Description : Luminous efficiency is least for a A. mercury vapor lamp B. low-wattage light bulb C. high-wattage light bulb D. fluorescent tube
Last Answer : B. low-wattage light bulb
Description : I have a 60 watt/120v clip-on lamp. What is the highest wattage of compact fluorescent bulb can I safely use in this lamp?
Last Answer : By the way, I mean actual watts on the fluorescent bulb, not replacement-watts. :)
Description : 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
Last Answer : ∙ a. Pulses of 694 nm red light
Description : Which of the listed types of lighting circuits does the diagram shown in the illustration represent? EL-0081 A. High pressure sodium B. Low voltage quartz C. Mercury vapor D. Standard fluorescent
Last Answer : Answer: D
Description : 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
Last Answer : B. light sensitivity
Description : 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
Last Answer : D. critical angle
Description : Why are visible-light LEDs not used for fiber optics? ∙ a. It has high losses ∙ b. It has short wave ∙ c. It has low attenuation ∙ d. It has weak signal
Last Answer : ∙ a. It has high losses
Description : A homeowner replaces a 65 watt incandescent bulb with a 15 watt compact fluorescent lamp. The light is on 2000 hours a year. If electricity cost 10 cents a kilowatt-hour, how much money is saved on the electric bill in one year? w) $50.00 x) $10.00 y) $5.00 z) $1.00
Last Answer : ANSWER: X -- $10.00
Description : The illustration shows a fluorescent light fixture. The ends of the lamp alternately glow and become dark, but the tube will not light. The most probable cause is that ____________. EL-0081 ... start the lamp D. component 'B' contacts are opening and closing thus prohibiting sufficient current flow
Last Answer : Answer: C
Description : A measure of conversion efficiency of a photodetector. ∙ A. Efficiency ∙ B. Responsivity ∙ C. Dark current ∙ D. Spectral response
Last Answer : B. Responsivity
Description : The _____ of a detector is the fraction of incident photons that produce a photoelectron or electron-hole pair ∙ a. Responsitivity ∙ b. Photon efficiency ∙ c. Aperture ∙ d. Quantum efficiency
Last Answer : d. Quantum efficiency
Description : 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
Last Answer : ∙ a. Atmospheric absorption
Description : Type of lasers that use organic dyes enclosed in glass tube for an active medium. ∙ A. liquid lasers ∙ B. plasma lasers ∙ C. neon lasers ∙ D. ruby lasers
Last Answer : liquid lasers
Description : 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
Last Answer : A. gas lasers
Description : The band of light frequencies that are too low to be seen by the human eye ∙ A. Infrared ∙ B. X-rays ∙ C. Visible ∙ D. Ultraviolet
Last Answer : Ultraviolet
Description : Can I use a higher wattage bulb in a lamp that states 40 watts?
Last Answer : You should not use a higher wattage bulb in a lamp that says 40 watts. The higher wattage could cause the lamp to catch fire due to the excess heat and could cause you serious electrical problems.
Description : The illustrated test is being conducted on the motor shown in the illustration, if the lamp lights dimly then ________. EL-0027 A. the bulb needs to be changed to one with a higher wattage rating B. ... D. a ground or partial ground is indicated, a check with a megger should confirm the lamp test
Description : The mechanical splice is best suited for ∙ A. quicker installation under ideal condition ∙ B. minimum attenuation losses ∙ C. field service conditions ∙ D. situations in which cost of equipment is not a factor
Last Answer : D. situations in which cost of equipment is not a factor
Description : Which light emitter is preferred for high-speed data in a fiber-optic system? ∙ A. incandescent ∙ B. LED ∙ C. neon ∙ D. laser
Last Answer : D. laser
Description : The law that states “When visible light of high frequency electromagnetic radiation illuminates a metallic surface, electrons are emitted” is known as ____________. ∙ A. Einstein law of photon ∙ B. Marconi’s law ∙ C. Maxwell’s law ∙ D. Plank’s law
Last Answer : D. Plank’s law
Description : The band of light frequencies that are too high to be seen by the human eye. ∙ A. Ultraviolet ∙ B. Visible light ∙ C. Infrared ∙ D. Yellow
Last Answer : ∙ C. Infrared
Description : An increase in light intensity produces fast optic switching due to ∙ a. Increase in index of glass ∙ b. Amplification of optical signal ∙ c. High gain ∙ d. Photoconductivity
Last Answer : b. Amplification of optical signal
Description : An important requirement for successful transmission system using light ∙ a. Powerful, reliable light source ∙ b. Strong glass ∙ c. Reliable, high cost transmission medium ∙ d. Powerful regenerators
Last Answer : a. Powerful, reliable light source
Description : Which light emitter is preferred for high speed data in a fiber-optic system ∙ a. Incandescent ∙ b. LED ∙ c. Neon ∙ d. Laser
Last Answer : ∙ d. Laser
Description : After turning on the fluorescent lamp shown in the illustration, you note that the ends of the tube alternately glow and becomce dark without illuminating the center. The most obable cause for ... the lamp D. component 'B' contacts are opening and closing thus prohibiting sufficient current flow
Description : A common fluorescent tube contains (a) sodium vapour (b) argon at low pressure (c) mercury vapour at low pressure (d) mercuric oxide and neon
Last Answer : Ans:(c)
Description : Refraction is the ∙ A. bending of light ∙ B. reflection of light waves ∙ C. distortion of light waves ∙ D. diffusion of light waves
Last Answer : A. bending of light
Description : The main benefit of light wave communications over microwaves or any other communications media are ∙ A. lower cost ∙ B. better security ∙ C. wider bandwidth ∙ D. freedom from interface
Last Answer : C. wider bandwidth
Description : EMD is best described by which statement? ∙ A. 70 percent of the core diameter and 70% of the fiber NA should be filled with light. ∙ B. 70 percent of the fiber diameter and 70% of the ... be measured at the output. ∙ D. 70 percent of the unwanted wavelengths should be attenuated by the fiber.
Last Answer : 70 percent of the core diameter and 70% of the fiber NA should be filled with light.
Description : The speed of light in plastic compared to the speed of light in air is ∙ A. less ∙ B. more ∙ C. the same ∙ D. zero
Last Answer : A. less
Description : 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
Last Answer : D. modal dispersion
Description : 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. greater than ∙ C. equal to ∙ D. zero
Last Answer : ∙ B. greater than
Description : A popular light wavelength fiber-optic cable is ∙ A. 0.7 micrometer ∙ B. 1.3 micrometer ∙ C. 1.5 micrometer ∙ D. 1.8 micrometer
Last Answer : B. 1.3 micrometer
Description : 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 ... . the ratio of the input power to output power ∙ D. the ratio of output current to input current
Last Answer : the ratio of the diode output current to the input optical power
Description : 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
Last Answer : D. transit time
Description : The leakage current that flows through a photodiode with no light input ∙ A. dark voltage ∙ B. dark impedance ∙ C. dark power ∙ D. dark current
Last Answer : D. dark current
Description : A pn-junction diode emits light by spontaneous emission ∙ A. LED ∙ B. APD ∙ C. PIN
Last Answer : A. LED
Description : 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
Last Answer : Use a single-mode fiber
Description : 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
Last Answer : A. modal dispersion
Description : 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
Last Answer : C. 0.5 dB
Description : 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
Last Answer : A. using a monochromatic light source
Description : 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
Last Answer : D. wavelength dispersion
Description : 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
Last Answer : ∙ C. -35 dBm
Description : It is caused by hydroxide ions in the material ∙ A. visible light absorption ∙ B. infrared absorption ∙ C. ultraviolet absorption ∙ D. ion resonance absorption
Last Answer : D. ion resonance absorption
Description : t 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
Last Answer : B. infrared absorption
Description : 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
Last Answer : ultraviolet absorption
Description : 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
Last Answer : B. absorption loss
Description : Which of the following is not a factor in cable light loss? ∙ A. reflection ∙ B. absorption ∙ C. scattering ∙ D. dispersion
Last Answer : A. reflection
Description : 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
Last Answer : A. power loss