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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 nearpoint 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 sincwater = 1.33/1.59, and cwater = 56.8...
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 Spring '08
 Mckay

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