职称英语在线答题

每日一练：职称英语考试理工类每日一练(2018/7/31)
【单选题】

Solar Power without Solar Cells
A dramatic and surprising magnetic effect of light discovered by University of Michigan Researchers 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　toa 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 moment 3. 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 ina 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 centimeter 8. Sunlight isn't this 　61　on its own, but new materials are being sought that would work at lowerintensities, Fisher said.
“In our most recent paper, we show that incoherent light 9 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, youhave to do 　64　semiconductor processing,” Fisher said.“All we would need are lenses to focus the light and a fiber to guide it. Glassworks for 　65　.It's already made in bulk, and itdoesn'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