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3. 2 Exam #4 on Monday !!!! Final Exam on Saturday

4. THE REFRACTIVE INDEX OF LIGHT IN A MEDIUM IS DEFINED AS Definition 3

5. FOR A WAVE From Your Previous Life (2053) 4

6. 5 The Wave Nature of Light The law of refraction is explained by Huygen’s Principle The little wavelets move slower in medium 2 than in medium 1. Doing the tangent shows how the wave fronts bend.

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8. 7 The Wave Nature of Light

9. 8 Snell’s Law of Refraction Law of Reflection

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13. 12 At the critical angle and beyond, only reflection is possible.

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15. Application: Undersea Cable 14 A cross section of a submarine communications cable. 1 - Polyethylene 2 - Mylar tape 3 - Stranded steel wires 4 - Aluminium water barrier 5 - Polycarbonate 6 - Copper or aluminum tube 7 - Petroleum jelly 8 - Optical fiberscross sectionPolyethyleneMylarsteelAluminiumPolycarbonatePetroleum jellyOptical fibers Lengths of 100 KM are possible before amplification is necessary. Thousands of conversations can be carried on a single fiber.

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