单选题A The lifecycle of trees.B The number of trees.C The intensity of solar burning.D The quality of air.

共用题干
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 effects of the mag-
netic 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 matenal,gets absorbed and
creates heat.Here,we expect to have a very low heat load.Instead of the light being absorbed,energy is
stored in the magnetic moment.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 unde-
tected brand of"optical rectification",says William Fisher,a doctoral student in applied physics.In tradi-
tional 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 centimeter. 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 light 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 usable energy.That's
equivalent to today's commercial-grade solar cells.
"To manufacture modern 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.Glassworks for
_________ (65).It's already made in bulk,and it doesn't require as much processing.Transparent
ceramics might be even better."

_________(60)
A:material
B:device
C:detector
D:meter

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Google's Solar Energy Gambit（策略）

Google is making its largest investment yet in clean energy,setting up a $280 million fund to finance home solar rooftop（屋顶）installations.
The search giant announced today it was teaming up with the Silicon Valley's Solar City一a company chaired by Paypal co-founder and Tesla Motors executive Elon Musk一in an effort to break down the biggest barrier to solar energy adoption:the cost."It's a great way to support installations going into more homes,"said Google spokesperson Parag Chokshi.The $280 million fund is the largest fund ever created for residential solar in the United States,according to Solar City,which has raised a total of$I.28 billion in financing capacity during its five-year history.
Google over the past several years has invested in large,utility-scale wind and solar,enhanced geothermal（地热）energy,and other renewable energy projects,for a grand total of more than $680 million in the sector. But today's deal is not only Google's largest foray（突袭）into the sector, it is its first investment in distributed energy. Based in San Mateo,California,less than 20 miles north of Google's Mountain View headquarters,Solar City describes itseff as a solar power service provider. The idea is that people want affordable,clean energy一but they often can't afford to buy a photovoltaic system upfront. Solar City is one of a number of companies that have attempted to help people overcome that cost hurdle（障碍）by leasing,instead of owning their rooftop solar systems.
Solar City's leases and power-purchase agreements to homeowners,businesses,and schools promise a lower monthly electricity bill(including a set payment to Solar City in addition to utility payments)than customers would get with their usual electricity from the grid.Solar City not only finances these photovoltaic projects,but also designs,installs,monitors,and maintains the systems. Recently,since buying the assets of a company called Business Solutions last year,Solar City has also begun offering energy audits and small home improvements(like installing programmable thermostats)that can make a big difference in energy use.
Until now,Solar City has financed most of its 15,000 projects through banks,Chief Executive Lyndon Rive said in an interview. But the problem is only about a half dozen banks are doing solar financing,he said.So in order for Solar City's model to achieve"true scale,"it must"unleash the available capital of corporate America,"he said.Rive is hopeful that Google's move today will set an example for other corporations to make similar investments.

Google is the biggest clean energy company in the world.
A:Right
B:Wrong
C:Not mentiond