Evaluation 1 "Basic Theory"

Q1 Which company invented the first low loss fiber used in telecommunications? Corning Siemens Sun Systems Optical Cable Corporation Answer CORRECT, see Optical Theory Section WRONG, Siemens make fiber product WRONG, they make computers and PC software WRONG, they do make cable but did not invent low loss fiber Q2 Which statement describes how photons are created? The nucleus of the silica atom freely emits photons when bombarded with light Neutrons are released by electrons striking them after heat is applied Atoms strike neutrons which emit photons after radiation displacement Electrons are displaced from their atomic orbit that causes photon emission Answer WRONG, not from pure silica WRONG, no, this is not how science describes emission WRONG, no, this is not how science describes emission CORRECT Q3 What does the term refraction mean? When photons pass through two crystalline materials with different densities the light path bends changing the direction of the photons When light travels through space and is affected by solar flares When photons strike a high-density material and rebound like a mirror When light travels through a single density material it bounces back Answer CORRECT WRONG, this does not describe refraction WRONG, this is reflection WRONG, this could be backscatter or reflection Q4 What are the names of the various parts of a fiber strand? PVC buffer, acrylate cladding, silica core silica buffer, silica core, silica cladding silica glass, doped glass, polyethylene glass PVC buffer, acrylate buffer, cladding, core Answer WRONG, what about the cladding WRONG, not a silica cladding WRONG, not polyethylene glass, no such thing CORRECT Q5 Why do we use graded index cores in multimode fiber? to eliminate photons taking too long to travel down the center of the core and arriving later than the photons travelling down the cladding laye to compensate for variations in core consistency by minimising photonic wavelength dispersion thus extending laser life because single mode fibers use step index cores to compensate for various wavelengths travelling in different paths within the core of the fiber, to try to eliminate modal and pulse dispersion Answer WRONG, photons are not used in the cladding layer WRONG, it has nothing to do with Laser life WRONG, altough true it does not answer the question CORRECT Q6 What is the name of the device that converts light into electricity? thyristor photodetector triad zener diode Answer WRONG, this is a power electronic switch CORRECT WRONG, this is an electronic device WRONG, this is a specialised electrnic device Q7 When we discuss the spectrum of a light source what are we referring to? the light sources general focusing ability the light sources consumption of power the light sources ability to absorb electricity the light sources generated wavelengths Answer WRONG, no, this is a reference to Numerical Aperture WRONG, power effects output intensity and wavelength in VCSELs WRONG, absorbing power generates light and heat CORRECT, wavelengths are part of the spectrum Q8 Why is it important to understand the refractive index of glass fibers? because different densities accelerate different wavelengths because different wavelengths travel at different speeds in different densities because different densities of silica make no difference to speed because different wavelengths travel at the same speed in different densities Answer WRONG, not acceleration CORRECT, we use this to measure with an OTDR WRONG, yes they do, the denser the slower WRONG, no they travel at different speeds Q9 The main reason fibers don't break easily when bent is due to what? fiber is very resilient and tough acrylate and PVC buffer coatings the cable protects the fiber from excessive bending the cladding protects the core from breaking Answer WRONG, although true the answer does not explain why CORRECT, these layers provide the mechanical stength WRONG, although true the answer does not explain why the fibers don't break WRONG, the core cladding is one glass strand, it will break Q10 What type of light is emitted from a LED? stimulated emission spontaneous emission spontaneous and stimulated emission aggravated emission Answer WRONG, this happens in Lasers CORRECT WRONG, only in Lasers WRONG, angry photons, that's new!!!