p235w11_practice_exam_3_2_sol

It acts like a closed end for the tube so you expect

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Unformatted text preview: s makes the lowest frequency vs/0 = 340 m/s / (4*1 m) = 85 Hz. B: (2 points) To what depth must you fill the tube to make this resonant frequency 500 Hz? To make this fundamental frequency 500 Hz, you’ll need a length: f = 340 / (4*L) so the length is L = 340 / (4*500) = 0.17 m. To make the tube have this much water, you need to fill it to 1.83 m deep. 15: (5 points) Two very narrow slits separated by a distance dsep will produce interference maxima at angles give by sin(max) = n/dsep. Explain how this pattern will change if we instead make a long array of 100 identical slits, each separated from the next by the same distance dsep. What features of the interference pattern will remain the same, and what features will change? The locations of the maxima remain in the same places, but the maxima become much narrower and are separated by regions which contain essentially no light. 16: (5 points) If you are farsighted, what is wrong with your eye, and what sort of lens (converging or diverging) is needed to fix this problem? Why will this sort of lens do the job? Draw a ray diagram to illustrate your point. A farsighted person has eyes which bend light too little. They can comfortably focus light from distant objects (which needs little bending) but fail to focus light from objects nearby (which need a lot of bending). In effect, their near-point is farther away than is typical (more than the usual 25 cm or so). To correct this vision, you need to add more bending of light. Uncorrected Corrected 17: (5 points) A piece of glass surrounded by air will exhibit total internal reflection when light rays reach its surface at angles greater than 39. What is the minimum angle required for total internal reflection if this piece of glass is instead submerged in water with an index of refraction of 1.33? From the first fact, we use sinc = n1/n2 to find 0.63 = n1/n2, and n2 = 1.59. Then when we place it in water, we get sinc-water = 1.33/1.59, and c-water = 56.8...
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