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2012年考研欧博娱乐精选背诵045

文章分类:考研 宣布工夫:2017-7-14 10:19:40

  The Source of Energy

  A summary of the physical and chemical nature of life must begin, not on the Earth, but in the Sun; in fact, at the Sun's very center. It is here that is to be found the source of the energy that the Sun constantly pours out into space as light and heat. This energy is liberated at the center of the Sun as billions upon billions of nuclei of hydrogen atoms collide with each other and fuse together to form nuclei of helium, and in doing so, release some of the energy that is stored in the nuclei of atoms. The output of light and heat of the Sun requires that some 600 million tons of hydrogen be converted into helium in the Sun every second. This the Sun has been doing for several thousands of millions of years. The nuclear energy is released at the Sun's center as high-energy gamma radiation, a form of electromagnetic radiation like light and radio waves, only of very much shorter wavelength. This gamma radiation is absorbed by atoms inside the Sun to be reemitted at slightly longer wavelengths. This radiation, in its turn is absorbed and reemitted. As the energy filters through the layers of the solar interior, it passes through the X-ray part of the spectrum eventually becoming light. At this stage, it has reached what we call the solar surface, and can escape into space without being absorbed further by solar atoms. A very small fraction of the Sun's light and heat is emitted in such directions that after passing unhindered through interplanetary space, it hits the Earth.

  全文翻译:能量的泉源

  概说生命的物理和化学特性必需始于太阳--确切地说,是太阳的中心,而非地球。 能 量来自太阳的中心。 在这里,太阳不绝地以光和热的方式向空间倾注出能量。 数十亿计的 氢原子核在太阳的中心碰撞而且聚变天生氦。 在此进程中一局部本来贮存于原子核中的能 量被开释出来。 太阳所发生的光和热需求每秒将六亿吨氢转化为氦。 如许的转化在太阳中曾经继续几十亿年了。 核能在太阳的中心被开释为高能的伽马射线。 这是一种电磁射线, 就象光波和无线电波一样,只是波长要短得多。这种伽玛射线被太阳内的原子所吸取,然 后重新开释为波长稍长一些的光波。 这新的射线再次被吸取,然后开释。 在能量由太阳外部一层层浸透出来的进程中,它颠末了光谱中 X 射线局部,最初酿成了光。 在此阶段,能量抵达我们所称的太阳表层,而且团圆到空间而不再被太阳原子所吸取。 只要很小一局部 太阳的光和热由此偏向开释出来,而且未被阻挠,穿越星空,离开地球。

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