ENGRI111_HW3_2004 - 3. Under what conditions of incident...

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ENGRI 111 Homework #3 Due Wednesday, September 29, 2004 1. The band gap of several materials is given below. What is the color of each material (explain your reasoning briefly ) ? Material Eg/eV C(diamond) 5.4 ZnS 3.6 ZnO 3.2 CdS 2.4 HgS 2.1 GaAs 1.4 2. A B&W photographic film contains silver halide particles embedded in a polymer. When the silver halide particles are illuminated by a light of sufficient energy, conduction band electrons and valence band holes are created. The electrons can move through the silver halide particle and they can combine with silver ions to form a neutral silver atom. The band gap in silver halide is about 2.7 eV. a.) Is silver halide sensitive to visible light? b.) After a film is exposed to a subject, why can it not be handled in daylight? c.) Why can it be handled in red light?
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Unformatted text preview: 3. Under what conditions of incident angle and refractive index is the incident beam fully reflected when light travels across two different materials? 4. The core of optical fibers is made of a drawn fiber of SiO 2 . a.) Describe one type of i) chemical impurity ii) physical defect that could be problematic to the efficiency of transmission and explain how each would be disruptive. (Hint: We are not looking so much for specific impurities as an explanation of what type of impurities might be problematic and how their presence would be disruptive.) b.) One advantage of fiber optics is that the fibers can transmit light of many different energies. Are there any limitations on possible energies for transmission?...
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