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Solar Power without Solar Cells
A dramatic and surprising magnetic effect of light discovered by University of Michigan1researchers could lead to solar power without traditional semiconductor-based solar cells.
The researchers found a way to make an “optical 51 ,” said Stephen Rand, a professor in the departments of Electrical Engineering and Computer Science, Physics and Applied Physics.
Light has electric and magnetic 52 . Until now, scientists thought the effect of the magnetic field were so weak that they could be 53 . What Rand and his colleagues found is that at the right intensity, when light is traveling through a material that does not 54 electricity, the light field can generate magnetic effects that are 100 million times stronger than previously expected. Under these circumstances, the magnetic effects develop strength 55 to a strong electric effect.
“This could lead to a new kind of solar cell without semiconductors and without absorption to produce charge separation, ” Rand said. “In solar cells, the 56 goes into a material, gets absorbed and creates heat. Here, we expect to have a very low heat load2. Instead of the light being absorbed, energy is stored in the magnetic moment3. Intense magnetization can be induced by intense light and then it is ultimately capable of providing a capacitive power 57 What makes this possible is a previously undetected brand of “optical rectification,” says William Fisher, a doctoral student in applied physics. In traditional optical rectification, light's electric field causes a charge separation, or a pulling 58 of the positive and negative charges in a material. This sets up a voltage, similar to 59 in a battery.
Rand and Fisher found that under the right circumstances and in right types of materials, the light's magnetic field can also create optical rectification. The light must be shone through a 60 that does not conduct electricity, such as glass. And it must be focused to an intensity of 10 million watts per square centimeter8. Sunlight isn't this 61 on its own, but new materials are being sought that would work at lower intensities, Fisher said.
“In our most recent paper, we show that incoherent light9 like sunlight is theoretically almost 62 effective in producing charge separation as laser light is,” Fisher said.
This new 63 could make solar power cheaper, the researchers say. They predict that with improved materials they could achieve 10 percent efficiency in converting solar power to useable energy. That's equivalent to today's commercial-grade solar cells.
“To manufacture modem solar cells, you have to do 64 semiconductor processing,” Fisher said. “All we would need are lenses to focus the light and a fiber to guide it. Glass works for 65 .It's already made in bulk, and it doesn't require as much processing. Transparent ceramics might be even better. ”
51. A. disc B. fiber C. instrument D. battery
52. A. applications B. components C. resources D. differences
53. A. concerned B. ignored C. expected D. noticed
54. A. conduct B. produce C. use D. consume
55. A. reactive B. preferable C. due D. equivalent
56. A. light B. electricity C. chemical D. gas
57. A. plant B. source C. equipment D. line
58. A. up B. down C. apart D. together
59. A. this B. those C. that D. these
60. A. material B. device C. detector D. meter
61. A. bright B. faint C. visible D. intense
62. A. more B. as C. much D. such
63. A. skill B. technology C. miracle D. prototype
64. A. extensive B. interactive C. selective D. intensive
65. A. all B. some C. others D. both
參考答案:
DBBAD ABCCA DBBAD
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