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How they work
In low-energy bulbs an electric discharge passes through argon gas containing mercury, which generates UV light. This in turn activates the coating on the inside surface of the bulb, which shines brightly. The coating includes five rare elements: cerium, europium, lanthanum, terbium and yttrium. They glow red, green and blue, which together we perceive as white light.
What's inside?
Lanthanum (La, element 57; emits green light)People suffering from chronic kidney dysfunction generally have too much phosphate in their blood, which can result in a painful bone condition. Lanthanum carbonate pills will prevent any phosphate from being absorbed in the stomach.
Mercury (Hg, element 80)Although mercury is an environmental toxin, the 3mg in a low-energy lightbulb is less than the mercury that would be emitted from a coal-fired power station providing the electricity to light a conventional lightbulb. However, careful disposal is still necessary.
Terbium (Tb, element 65; emits green light)Terbium is rarer and more expensive than platinum. An unusual property of the terbium alloy tefenol is that it will lengthen or shorten in response to a varying magnetic field. It is used in the Soundbug which turns any smooth surface, such as a window, into a loudspeaker.
Argon (Ar, element 18)Argon is extracted from liquid air. It is completely unreactive to electrical discharges passed through it, regardless of strength. Its most exotic use is in the tyres of luxury cars where it protects the rubber and ensures less tyre noise at high speed.
Cerium (Ce, element 58; emits green light)Cerium oxide is also used in catalytic converters – it helps metals such as platinum or rhodium to remove pollutants. Thus CO becomes CO2 and nitrogen oxides become N2. Cerium is also used in selfcleaning ovens.
Europium (Eu, element 63; emits red and blue light)If you suspect a euro note is a forgery, submit it to UV light – and if parts of it glow red, it’s OK. The red comes from europium in the special printing inks. Rather puzzlingly, europium was found in much higher concentrations than expected in samples of rock brought back from the Moon.
Yttrium (Y, element 39; emits red light)Yttrium oxide glass is heat- and shockresistant, and used for camera lenses. Yttrium is used in superconductors, which can conduct electricity without any loss of energy; and yttrium aluminium garnet is used in lasers and makes sparkling diamond-like gems.
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This article was originally published by WIRED UK
