In the video, hosts Ross Exton and Nerys Shah use little more than a microwave oven and a chocolate bar to show how to calculate the speed of light. The video doesnt make it perfectly clear how measuring the melted bits on a chocolate bar relates to the speed of light. But breaking it down a little more just requires taking a look at some of the units used in their measurements. . Hertz is the physics stand-in for “cycles per second.” The microwave used in the video produced light waves with a frequency of 2,450,000,000 Hertz, or that many cycles per second. Going from peak to peak in a wave—in this case the distance between the first and third melted bit of chocolate—is one cycle. Exton and Shah measured that distance as 0.12 meters, or 0.12 meters per cycle. Multiplying something measured in “meters per cycle” by something in “cycles per second” will give a measurement in “meters per second.” Thats the waves velocity—the speed of light. . The trick that makes the At Bristol teams approach work is that we in the modern era already know a few important things about light: that it has a finite speed, and that that speed is largely constant. We also have the benefit of physicists having already teased out the relationship between wave length, frequency and velocity. . When Ole Rømer looked to Jupiter and first deduced the speed of light he came up with 214,000,000 meters per second. See: amnh.org/education/resources/rfl/web/essaybooks/cosmic/p_roemer.html . “This measurement, considering its antiquity, method of measurement, and 17th century uncertainty in exactly how far Jupiter was from the Earth, is surprisingly close to the modern value of [299 792 458] meters per second,” says Dave Kornreich for Cornell. . Using a microwave and a chocolate bar Exton and Shah got 294,000,000 meters per second—not bad for a little bit of kitchen science. . Text from: smithsonianmag/smart-news/theres-easy-and-tasty-way-measure-speed-light-home-180952245/#F0KDY4xtkWMsUqKE.99
Posted on: Sat, 16 Aug 2014 21:57:05 +0000
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