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  3. Although it symbolises a bright idea, the traditional incandescent light bul

Although it symbolises a bright idea, the traditional incandescent light bul

游客2024-01-02  33
问题     Although it symbolises a bright idea, the traditional incandescent light bulb is a dud. It wastes huge amounts of electricity, radiating 95% of the energy it consumes as heat rather than light. Its life is also relatively short, culminating in a dull pop as its filament fractures. Now a team of researchers has devised a light bulb that is not only much more energy-efficient—it is also expected to last longer than the devices into which it is inserted. Moreover, the lamp could be used for rear-projection televisions as well as general illumination.
    The trick to a longer life, for light bulbs at least, is to ensure that the lamp has no electrodes. Although electrodes are undeniably convenient for plugging bulbs directly into the lighting system, they are also the main reason why lamps fail. The electrodes wear out. They can react chemically with the gas inside the light bulb, making it grow dimmer. They are also difficult to seal into the structure of the bulb, making the rupture of these seals another potential source of failure.
    Scientists working for Ceravision, a company based in Milton Keynes, in Britain, have designed a new form of lamp that eliminates the need for electrodes. Their device uses microwaves to transform electricity into light. It consists of a relatively small lump of aluminium oxide into which a hole has been bored. When the aluminium oxide is bombarded with microwaves generated from the same sort of device that powers a microwave oven, a concentrated electric field is created inside the void.
    If a cylindrical capsule containing a suitable gas is inserted into the hole, the atoms of the gas become ionised. As electrons accelerate in the electric field, they gain energy that they pass on to the atoms and molecules of the gas as they collide with them, creating a glowing plasma. The resulting light is bright, and the process is energy-efficient. Indeed, whereas traditional light bulbs emit just 5% of their energy as light, and fluorescent tubes about 15% , the Ceravision lamp has an efficiency greater than 50%.
    Because the lamp has no filament, the scientists who developed it think it will last for thousands of hours of use—in other words, for decades. Moreover, the light it generates comes from what is almost a single point, which means that the bulbs can be used in projectors and televisions. Because of this, the light is much more directional and the lamp could thus prove more efficient than bulbs that scatter light in all directions. Its long life would make the new light ideal for buildings in which the architecture makes changing light bulbs complicated and expensive. The lamps’ small size makes them comparable to light-emitting diodes but the new lamp generates much brighter light than those semiconductor devices do. A single microwave generator can be used to power several lamps.
    Another environmental advantage of the new design is that it does not need mercury, a highly toxic metal found in most of the bulbs used today, including energy-saving fluorescent bulbs, fluorescent tubes and the high-pressure bulbs used in projectors. And Ceravision also reckons it should be cheap to make. With lighting accounting for some 20% of electricity use worldwide, switching to a more efficient system could both save energy and reduce emissions of climate-changing greenhouse gases.
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答案                             永恒的灯光
    尽管传统的白炽灯象征着光明，但实际上却没有多大用处。因为它耗电量大，消耗的95％的电能只是用来发热而没有发光。同时它的使用寿命也很短，随着白炽灯发出沉闷的砰声时，灯丝就断裂了。现在一组研究人员发明了一种新电灯，这种灯不仅能有效地利用电能，还比嵌入的装置更耐用。此外，这种灯不仅能用于一般照明，还能运用到背投电视中。
    至少对白炽灯而言，想它更耐用的秘密就是要确保它没有电极。不可否认，正是因为它有电极，人们才能便捷地把电灯运用到照明系统中，但这也是灯泡容易坏的主要原因。电极磨损了，就会与灯泡内的气体发生化学反应，这样电灯的光线也就逐渐变得昏暗。此外，也很难把电极密封在灯泡里。密封不好也是电灯坏掉的另一个潜在原因。
    来自凯诺森公司(位于英国米尔顿凯恩斯)的科学家发明了一种不需要电极的新型灯。利用微波把电能转换成光能。在灯内安置一块小型氧化铝，当氧化铝接触到微波(与驱动微波炉的微波产生原理相似)时就会在灯内的真空中形成一个集成电路。
    如果把装有适量气体的圆柱形容器插入灯内，气体的原子就会变成离子。当电场的电子加速时，电极就获得了能量，并且跟气体原子核分子相撞时能传递能量，这样就会产生能发光的等离子气体。这一过程所发出的光很明亮，并且能源也得到了有效利用。确实，传统的电灯泡只将5％的能量转化为光能，荧光管则用15％的能量换化成光能，而凯诺维森灯的能源利用率至少有50％。
    因为这种灯没有灯丝，发明者认为它能持续用上数千个小时，换句话说，也就是有几十年的时间。而且它发出的光几乎都源于一个点，这就意味着可以把这种灯运用到投影仪和电视机中。也正是因为如此，它发出的光更定向，因此也就比光线四散的白炽灯更有效。对于那种需要为不断更换电灯带来高花销的建筑物而言，耐用的凯诺维森灯便成了理想灯饰。凯诺维森灯的小巧外形比得上发光的二极管，但是它比半导体装置发出的光更明亮。只要用一个微型发电器就能驱动数个这类新型灯。
    它的新颖设计还有个环保优点，它没有水银这种高毒性的金属。现在大部分的灯管都用了水银，如：省电荧光灯泡、荧光灯管和放映机内的高压灯管。Ceravision还认为制作这种灯的成本很低。只要使用现今世界上大概20％的电能就能转化成一个更有效的系统，既节能又能减少改变气候的温室气体的排放。
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