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用同样材料作成的物体间相互摩擦能否起电?
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答:物体在通常情况下,原子核里的正电荷与核外的负电荷数目相等,因而呈中性,也叫“净电荷”为零.只有当物体有多余的电子或失去一部分电子时,才带负电或正电,这时“净电荷”不为零.若两个由相同材料制成的物体相互摩擦,由于它们原子核对电子的束缚能力相同,得失电子的机会相同,因而很难使它们能带上异种电荷.

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    Bigger isn't always better. Many scientists will agree. This year the Nobel Prize gave the biggest prizes to findings on the smallest things. Self-eating cells

    This year's winner of the Nobel Prize in Medicine is from Japan. According to his research, cells (细胞) sometimes "eat" themselves to keep healthy. In other words, cells can break down old ones and use the useful parts to make new cells, or to fight off viruses (病毒). This new finding could help scientists fight many diseases.

Small machines

    Three scientists from France, the United Kingdom and the Netherlands (荷兰) won the Nobel Prize in Chemistry for their work on small machines. How small? Well, they are a thousand times thinner than a strand (缕) of hair. We can't see them with only our eyes! This technology will open a whole new world for us. For example, we could make very small robots in the future. A doctor could put them into our body. Like policemen, the robots look for the ill parts in our body, and send the medicine right there.

Super-state

As teachers said in your physics class, most things in the world are in three states: solids (固体), liquids (液体) and gases . But at very low or high temperatures, things can turn into a strange state. For example, break down things to their smallest pieces and we get "atoms" (原子). Like Lego building blocks, atoms usually add up to become a 3-D thing, like a box. But atoms in the strange state don't. They stay together and become a flat thing, like a piece of paper.

    This is a new finding of three British-born scientists. And they won the Nobel Prize in Physics this year. They hope to use things in this strange state to make new materials.

About the Prize

    The Nobel Prize was started by Swedish inventor, Alfred Nobel in 1895. It gives prizes to great science research and the people behind it. Every year in October, the Royal Swedish Academy of Sciences decides who wins. It includes six prizes: chemistry, physics, physiology (生理学) or medicine, peace, literature (文学) and economic. This year each winner gets a medal and prize money of more than 6 million yuan.

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