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Unformatted text preview: Version 014 – Exam3 – shih – (56310) 1 This printout should have 12 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. 001 10.0 points Light at a frequence of 4 × 10 14 Hz goes through two slits and has its second inter erence null deflected at an angle θ . What frequency will have its third interfer ence null deflected at this same angle? 1. 3 . 37 × 10 14 2. 2 . 67 × 10 14 3. 9 . 61 × 10 14 4. 1 . 50 × 10 14 5. 8 . 55 × 10 14 6. 6 . 67 × 10 14 correct Explanation: The angle of an interference null of a two slit experiment is d sin θ = parenleftbigg m + 1 2 parenrightbigg λ = parenleftbigg m + 1 2 parenrightbigg c f , where d is the separation of the slit. The first frequency f 1 at the second inter ference null ( m = 1) satifies d sin θ = 3 2 c f 1 , while the second frequency f 2 at the third interference null ( m = 2) satisfies d sin θ = 5 2 c f 2 . Thus f 2 f 1 = 5 c 2 d sin θ 3 c 2 d sin θ = 5 3 f 2 = 5 3 f 1 = 5 3 (4 × 10 14 Hz) = 6 . 66667 × 10 14 Hz . 002 10.0 points Two parallel polarizer disks are aligned with the transmission axis of the first oriented at an angle θ 1 clockwise from the vertical, and that of the second at an angle θ 2 clockwise from the vertical, with 0 < θ 1 < θ 2 . A horizontal beam of polarized light with intensity I and the polarization direction pointing vertically passes through both polarizers. The intensity I of the light is 1. I = I cos 2 θ 2 . 2. I = I cos 2 θ 1 cos 2 θ 2 . 3. I = I cos 2 θ 1 cos 2 θ 2 . 4. I = I cos 2 θ 1 . 5. I = I cos 2 θ 1 . 6. I = I . 7. I = I cos 2 θ 2 . 8. I = I cos 2 θ 2 cos 2 θ 1 . 9. I = I cos 2 θ 1 cos 2 ( θ 2 θ 1 ) . correct 10. None of these. Explanation: When polarized light passes through a polarizer, the transmitted intensity is I = I cos 2 θ , where θ is the angle between the di rection of polarization of the light and the axis of the polarizer. Now we have two successive polarizers, so the resulting intensity will be I = I cos 2 θ 1 cos 2 ( θ 2 θ 1 ) . 003 10.0 points A fiberoptic rod consists of a central strand of material surrounded by an outer coating. Version 014 – Exam3 – shih – (56310) 2 The interior portion of the rod has an index of refraction of 1.90....
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 Spring '10
 TSOI
 Physics, Light, Wavelength, Sin, doubleslit interference

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