[Note: Dr. Lenk found this second essay after re-calibrating his time machine. He, UBM, and the sponsor do not know which calibration was correct -- which future will come to pass. -- Ed.]
In 2014, just sixteen years ago, light bulbs were quite different from what they are today. At that time, most light bulbs used controlled heating of a metal to produce light, a process called incandescence. Correspondingly, the light bulbs were called incandescent bulbs. Today, of course, all light bulbs are made with Light Emitting Diodes, or LEDs. In this report, I'm going to explain how such a rapid and complete change occurred, especially in the face of a serious competing technology known as the Compact Fluorescent Lamp, or CFL.
To understand the background of this change, you must realize that incandescent bulbs were extraordinarily inefficient. Some 90% of the power that went in to heating the metal filament in the bulbs came out as heat, and only the remaining 10% was converted into light. In 2010, the governments of the world began banning incandescent bulbs in order to help conserve energy, and by 2014 the ban was pretty much complete.
The other technology
The other technology back then, CFLs, was also used in light bulbs. In fact, all sorts of lights used fluorescence, not just light bulbs, but also the tubes used to light offices. Fluorescent lamps and tubes, including CFLs, produced light and were quite efficient. They worked by generated a low-temperature plasma. (That is what the physicists call it -- it was actually something like 1100°C.) The plasma emitted deep-ultraviolet light, and a material that coated the outside of the lamp, called a phosphor, absorbed that light and re-emitted white light.
CFLs were on the market for many years before LED bulbs were, and were considerably cheaper. What could have happened that caused all lighting today to be made with LEDs rather than fluorescence? One part of the answer is that the performance of CFLs just wasn't as good as LED bulbs. Objects in the light of a CFL didn't look quite right, whereas LEDs produced a better light. Then LEDs got better at that a lot faster than CFLs did.
Another part of the answer is that CFLs weren't really that cheap. Governments were subsidizing them, providing rebates to consumers to make them seem inexpensive. And when the CFLs had to be upgraded to match the performance of LED light bulbs, they became more expensive too, so that the cost wasn't all that different.
The turning point
What really tipped the balance in the end was the accident at Fukishima in Japan (which strangely was close to the site of a nuclear accident just a few years earlier). With the mercury poisoning of so many school children, the Japanese government banned all fluorescent lighting. Other governments quickly followed suit. With incandescents and fluorescents both banned, the road was clear for the entire world to be using LED bulbs for all lighting today.
Teacher's comments:
Good report. You could have expanded a bit on the Fukishima disaster.
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