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Unformatted text preview: Howard (clh2528) Homework #1 shubeita (57885) 1 This print-out should have 13 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points A fiber optic cable ( n fiber = 1 . 67) is sub- merged in water ( n water = 1 . 33). What is the critical angle for light to stay inside the cable? Correct answer: 52 . 7884 . Explanation: Basic Concept: Snells law for total internal reflection n 1 sin c = n 2 sin 90 where c is the critical angle for total internal reflection. For total internal reflection, n 1 sin c = n 2 sin 90 For our problem, it is n fiber sin c = n water sin90 1 . 67 sin c = 1 . 33 sin 90 So, c = 52 . 7884 . 002 10.0 points A beam of white light is incident on a trian- gular glass prism with an index of refraction of about 1.5 for visible light, producing a spectrum. Initially, the prism is in a glass aquarium filled with air, as shown. I n c i d e n t L i g h t V i o l e t R e d Prism Spectrum Aquarium If the aquarium is filled with water with an index of refraction of 1.3, which of the following is true? 1. The violet light disappear. 2. The spectrum produced has less separa- tion between red and violet than that pro- duced in air. correct 3. The position of red and violet are reversed in the spectrum. 4. A spectrum is produced, but the deviation of the beam is opposite to that in air. 5. The intensity of the light increases. 6. There is no light come out of the prism. 7. The spectrum produced has greater sep- aration between red and violet than that pro- duced in air. 8. The red light disappear. 9. The spectrum has the same separation between red and violet as that produced in air. 10. No spectrum is produced. Explanation: Since water has a larger index of refrac- tion than air (but still smaller than the glass prism), the deviation of light beam caused by refraction will be smaller. I n c i d e n t L i g h t V i o l e t R e d Prism Spectrum Aquarium Thus, the spectrum produced has less sep- aration between red and violet than that pro- duced in air....
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- Spring '08