2. 外语
  3. The Tiniest Electric Motor in the World 1. Scientists recently made public the tiniest electric motor ever built. You could stuf

The Tiniest Electric Motor in the World 1. Scientists recently made public the tiniest electric motor ever built. You could stuf

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问题            The Tiniest Electric Motor in the World
1. Scientists recently made public the tiniest electric motor ever built. You could stuff hundreds of them into the period at the end of this sentence. One day a similar engine might power a tiny mechanical doctor that would travel through your body to remove your disease.
2. The motor works by shuffling atoms between two molten metal droplets in a carbon nanotube. One droplet is even smaller than the other. When a small electric current is applied to the droplets, atoms slowly get out of the larger droplet and join the smaller one. The small droplet, grows—but never gets as big as the other droplet—and eventually bumps into the large droplet As they touch, the large droplet rapidly sops up the atoms it had previously lost. This quick shift in energy produces a power stroke.  3. The technique exploits the fact that surface tension—the tendency of atoms or molecules to resist separating—becomes more important at small scales. Surface tension is the same thing that allows some insects to walk on water.
4. Although the amount of energy produced is small—20 microwatts—it is quite impressive in relation to the tiny scale of the motor. The whole setup is less than 200 nanometers on a side, or hundreds of times smaller than the width of a human hair. If it could be scaled up to the size of an automobile engine, it would be 100 million times more powerful than a Toyota Camry’s 225 horsepower V6 engine.
5. In 1988 , Professor Richard Muller and colleagues made the first operating micromotor, which was 100 microns across, or about the thickness of a human hair. In 2003, Zettl’s group created the first nanoscale motor. In 2006, they built a nanoconveyor, which moves tiny particles along like cars in a factory.
6. Nanotechnology engineers try to mimic nature, building things atom-by-atom. Among other things, nanomotors could be used in optical circuits to redirect light, a process called optical switching. Futurists envision a day when nanomachines, powered by nanomotors, travel inside your body to find disease and repair damaged cells.
A. An Introduction of a Toyota’s 225 Horsepower V6 Engine
B. A Description of the Nanomotor in Terms of Power and Size
C. Surface Tension
D. Previous Inventions of Nanoscale Products
E. The Working Principle of the Nanomotor
F. Possible Fields of Application in the Future
Paragraph 2______
选项
答案E
解析 本题考查的是对所读材料大意与主旨的掌握。第二段介绍了纳米发动机的工作原理。两小滴金属熔液通上微弱电流，大的小滴的原子就会缓慢逸出，进入小的小滴．后者体积不断增大，到一定阶段，就会与前者碰撞，这时，大的小滴便夺回它失去的原子，这就是一次power stroke(动力行程，动力冲程)。此时就会产生发动机的动力，原子如此来来去去运动，就像发动机活塞一样。这就是纳米发动机的工作原理，所以E是答案。
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