A Glowing Reputation
Paul explains why discharge tubes, such as fluorescent lights, glow.
It’s pretty easy to understand how a regular light bulb works. You run electricity through its filament, and it heats up, until it’s white-hotand glowing. But have you ever wondered why fluorescent lights glow, even though they don't contain a filament? If you thought it was magic, guess again - the correct answer is SCIENCE!
#1 Geissler's Glassblowing Cathode ray tubes aren't the only thing that you can do with vacuum tubes. In 1857, a fellow named Julius Pluker got his friend Heinrich Geissler to make some vacuum tubes at different pressures. Pluker saw that putting a high voltage across the tubes caused them to glow, and form pretty "striation" patterns. Poor old Pluker was more into science than business though, so it never crossed his mind that his spectroscopy and cathode ray experiments could have applications in commercial lighting.
#2 Moore Inventions In the 1890s, Daniel McFarlan Moore (one of Thomas Edison's employees) began tinkering around with Geissler's discharge tubes. He found that phosphor glowed when ultraviolet light shone on it, and decided to paint it onto a discharge tube that glowed ultraviolet to see what would happen. No doubt you saw this coming, but it made the phosphor glow - bright enough to light up a room.
#3 A Bright Idea Thomas Edison, who was getting famous for making regular, incandescent light bulbs at the time, was rather unimpressed by his employee's invention. Funnily enough, Moore wasn't impressed with Edison’s light bulbs, either. So, Moore left Edison's company and started his own. He sold the first fluorescent lights on the market in 1905. Over the last hundred years, the design has improved a bit, and fluorescent lamps are slowly beginning to replace the regular incandescent ones. What’s that sound? Probably Edison, rolling in his grave…
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