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Measure The Speed Of Light With Your Microwave
maddmike writes "There is a very interesting article on About.com that shows how to measure the speed of light using your microwave to melt chocolate. "
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I have over 70 freaks, do you?
Just try to measure the speed of dar. . .
Oh, nevermind.
KFG
if you're good at your job you can have your cake and eat it too
Banaaaana!
...don't try this at home. Theobroma cacao (chocolate) is a highly dangerous substance with known stimulant effects. It is also highly addictive and should be used with extreme caution. Overdose can cause morbid obesity, sluggishness, and death. Only qualified experts should handle this dangerous reagent at home.
I am experienced at handling this most hazardous material. Please wrap it carefully in a heatproof container, and mail it to me. It will be disposed of properly. (burp)
Honey, I shrunk the Cygwin
I think it took you a little too long to come up with that one
what would forrest gump think?
According to the website, using the formula, the speed of light is 24 cubits per moonphase.
Maybe we can unravel the mystery of the expansion of the early universe with a microwave and a set of unevenly expanding peeps. I envision a new era in science
could someone please provide me with the equation if mine has a turntable?
Is it just my microwave, or is the speed of light 2m/s ?
There is a very interesting article on About.com that shows how to measure the speed of light using your microwave to melt chocholate.
Big deal...I can measure Hubble's Constant by charring bagels in my toaster. Pffft.
you remove the turntable... as the article specifies
one of the first things it says is to remove the turntable............
RTFA. To quote the second sentence, "Remove the turntable from the microwave and replace with chocolate on a plate (so the plate does not rotate)"
Yikes, some people.
.sig
Um RTFA anyone???
He specifically says take the turntable out, somewhere buried so far deep in the article you'd never find it, you know the nether regions of space called the the second sentence.
Yay! I did that experiment! According to my calculations light in air travels at 783 km/h. Wow, that's fast!
Don't be so hash! The poster is clearly retarded and in need of more gentle encouragement.
I was just writing a wikipedia page yesterday on Famous Experiments, and that's the one I added. I read that Galileo tried measuring the speed of light the same way they measured sound -- by having two people stand a large distance apart, and flash a latern (for light) or make a sound. Subtract out the handler delay (a known quantity dependant on the person), and divide by two to get the speed of the wave. This works rather well for sound, but never worked for light.
To make laws that man cannot, and will not obey, serves to bring all law into contempt.
--E.C. Stanton
Short informative read:S peedOfLight/measure_c.html
http://math.ucr.edu/home/baez/physics/Relativity/
...Your Local Fire Department by placing some metal in your microwave and putting a blanket over it. =P
Anyone can melt chocolate or heat water in their microwave.
Real geeks use microwaves for what they were intended for... nuking free trial CDs from AOL.
http://physics.about.com/library/weekly/aa01270
The link given in the story here is for the second page.
Bah.. I'm waiting for chocolate wafer-transistors.
think.. eatable cpu's! or better.. eatable storage for the paranoid
- I choked on the red pill and now I'm stuck in limbo
Then the speed is 0.12m x 2.5 x 10**9 /s = 3 x 10**8 m/s
I thought it was 3.0 * 10**9
Mabey this was not such a good way to measure after all.
You cannot do it by measuring the dimensions of the magnetron cavities, because the calculation of the frequency based on dimensions assumes the thing you are trying to work out - the speed of light. Frequency counters that go up to 2.5GHz are a bit difficult to come by in most homes. One possibility might be to extract some energy from the cavity using a suitable antenna and mix it with the clock signal from a 2.4 or 2.53GHz motherboard, then try and pick up the resulting beat signal using a short wave or VHF radio. However, I'm not at all sure how to get the signal out of the P4.
Has anybody got a better and reasonably practical method of measuring the frequency?
Panurge has posted for the last time. Thanks for the positive moderations.
I liked the article, because chocolate is tasty.
Summary of the method used in the article:
* Slightly melt chocolate chips in your microwave
* Measure distance between melted spots
* This gives you (half) the wavelength of your oven
* Multiply by the frequency of your oven, you get the speed of light
That's certainly interesting, but guess what? Many scientists have done better (and much more expensive) measures, so we already know the speed of light quite well.
What we might not know as well is the frequency of your oven. So I suggest you reverse the above formula, and you measure the frequency of your oven (not always printed on the back, as the article admits) this way.
Chocolate is dark, like the universe.
Chocolate is semi-soft, like the universe.
Chocolate is an emulsion, like the universe.
Chocolate is good...and evil, like the universe.
Chocolate may be going into or coming out of a black hole, like the universe (I had to).
So, inevitably, this bean is, indeed, a universe unto itself.
Bah, too complicated. I'll just stand on a mountain and wait for my friend on a far away mountain to uncover his lamp at exactly 8:00. I'll measure the time delay, and divide by the distance between the mountains. What could go wrong? : )
If you still haven't figured it out, the article says to take out the turntable.
maddmike writes "There is a very interesting article on About.com that shows how to measure the speed of light using your microwave to melt chocholate. "
Bah, that's easy stuff. It's about time that About.com tackled the real holy grail of science - how to teach Slashdot editors to use a spelling checker.
"Accept that some days you are the pigeon, and some days you are the statue." - David Brent, Wernham Hogg
...marshmallows.
Maybe we can combine the methods, add graham crackers, and create C-smores!
Warning, do not try this at home if there are any women in the area. All i discovered was the speed of woman to the smell of mmelting chocolate = bloody fast
bah!*@%!
If you open that door fast enough.
microwave experiments and links
The metre is defined in terms of the speed of light, so by definition c=299792458 m/s
Pretty pointless trying to measure it really.
Quidquid Latine dictum sit, altum videtur (anything said in Latin sounds important)
It's 3x10^8 m/s
If I seem short sighted, it is because I stand on the shoulders of midgets
This experiment does not measure the speed of light. It measures the speed of microwaves.
I'm no physicist but, seems to me, 6cm would be 0.06m, so more like 3 x 10^7 per solid Girardehli testing.
As my microwave didn't have a frequency reading on the back, I will use the 2.5GHz "typical" value I found after a brief web search.
Thus: the wavelength is
Then the speed is 0.12m x 2.5 x 10^9
What changed under Obama? Nothing Good
Some brave souls try to correct me by pointing out that "the microwave particles" are so small they can't be seen, so are clearly smaller than the holes.
I then introduce the notion of particle/wave and laugh as I watch them go completely blank...
It would have to be an inverted soup bowl on my microwave to get it over the spindle. A plate wouldn't work as the clearance must be at least a couple of cm.
See my journal, I write things there
chocolate - is there anything it can't do....
anyone else notice this?
.6m x 2 = 0.12m
Thus: the wavelength is
Does it screw up the rest of the math?
...and you mostly like to...uhmm...dispose...such material originated from switzerland, eh? *g*
Actually, the speed of light is 299792458 m/s by definition/p>
So, given the frequency of your microwave a priori, this is actually a rather elaborate way of determining the length of a met{re|er} :-)
Wow you didn't understand the article at all. The point is to measure the hot spots, if you had the thing rotating the chocolate would melt evenly, creating a pool of chocolate. But since you take the turn table out, you get hot spots which you measure the distance between.
What this guy does is measuring the speed of microwaves, not light. In any case, if it needs 2 minutes to melt some chocolate, that's not very fast.
I was about to attempt this fascinating experiment but my stomach had... other plans
Couldn't they have created this experiment with something less tasty, like broccoli?!
Business \Busi"ness\, n.;
A scam in which all people involved perceive as beneficial...
The metre is defined in terms of the speed of light,...
:-)))
:-)
Wrong. The meter is defined by the distance from the Equator to the North Pole (divided 10 000 000).
So seeth the beauty of the metric system:
1000 Meters == one _Kilo_meter
one tenth of a meter == one _Deci_meter
one hundredth of a meter == one _Centi_meter
1 gram == one cube centimeter of water
1 _Kilo_gramm == 1000 cube centimeters of water == one Liter....
and so on. Get the picture?
Now how many feet to a mile was there again?
And what was that with Gallons and Pints?
Not to speak of those bizar 72 and 96 dpi that have spread all over the world... (grrrr.)
Coming to think of it: Flying to the moon is quite a stunt.
Flying to the moon using the imperial system is even more extraordinary astonishing. I remember Neil Armstrong explaining the depth of the moon dust in fractions of an inch.
Me actually wonders that you americans don't have something like 387,56 Cents to a Dollar or so.
BTW: I think we europeans have Mr. Napoleon to thank for this. Continental europeans that is. The British are a totally different issue. They got Napoleon at Waterloo and now look what they have from it: They have to live with the imperial system for all eternity.
We suffer more in our imagination than in reality. - Seneca
To the Canadian AC: The right to own guns did not kill this child, it was a stupid parent. I own 2 handguns and 3 hunting rifles. My child could not get to these, and the are in a 700 lb gun safe. However, our judicial system does need to start punishing these stupid parents who just leave guns laying around everywhere.
To the American AC: Please shut up. People like you make it seem like all Americans are stupid.
"The speed of light is equal to the wavelength multiplied by the frequency of an electromagnetic wave (microwaves and visible light are both examples of electromagnetic waves)"
Is it just me or does this seem like he's only measuring the speed of microwaves?
Is there a physicist in the house?
You can always use your network cables instead; brief description or full paper.
Anyone care to use the method with RFC1149 Avian Carrier Protocol, namely Using Ping to determine Speed of Flight!
Andrew Yeomans
the article really starts here
shame on the poster for linking to page two of a three page article, and shame on about.com for designing a webpage that doesn't actually allow you to go back one page to get to page one (it calls page 2 page one in it's navigation, however, in the page title, it is clear you are looking at page 2. Conclusion: web developers for about.com need shooting.)
you're wrong, or at least outdated: http://lamar.colostate.edu/~hillger/meter.htm
this is Slashdot we're talking about. I don't think a crowd of women is something regular denizens have to worry about very often.
There was this episode of Mystery Science Theater 3000 (Secret Agent Super Dragon?) where the main character flips a light switch, and about half a second later the light dimmed down. Crow said "Light travels slower in his world". Heh.
Hmmm.. sorry guys, it really is more of a visual joke.
"Derp de derp."
We did this experiment in physics a couple of years ago - with marshmallows. Mmm...
Oops, my bad. All Americans may not be stupid, but sometimes we do forget to preview our posts- "and are in a 700lb gun safe" should be "as they are in a 700 etc..."
But how many rods to the hogshead is that?
What's the velocity factor of chocolate?
Mea navis aericumbens anguillis abundat
I don't have a microwave oven, you insensitive clod!
Je fume. Tu fumes. Nous fûmes!
Most of the Microwaves available in the UK are multi-source and some kind of wave guide in them, so the experement will fail.
thank God the internet isn't a human right.
Forget about the speed of light, how long exactly in nano seconds does it take for a site to get Slashdotted?
How about an experiment?
If you use Linux, please help development of Autopac
whose name is choc'ho'late. She's everybody's favorite. She works at the speed of light and you melt.
--the funny jokes are always the dirty ones
Take the cheese to sickbay, the doctor should see it as soon as possible - B'Elanna Torres, "Learning Curve"
to play a second harmonic.
A slashdotting - you get the stick first and then the carrot !
Yeah it's pretty quick
Second problem is that it is actually difficult to stop something rotating. You need an inverted soup bowel or something to give clearance over the turntable drive peg.
Ok, if I use enough clearance to prevent rotation I get about 1cm between hot spots.
See my journal, I write things there
If you google for "speed of light" you get "News: Measure the Speed Of Light With Your Microwave - SLashdot - 2 hours ago"
Complete with (incorrect) overusage of CAPS and everything.
This experiment has no place outside the elementary school classroom. In fact, I think it has no place even there, because this method will be so wildly inaccurate that kids will learn the wrong speed of light.
Is it a wonder education is going to hell? We keep coming up with stupid, irresponsible "hack" methods of science that teach people the WRONG thing because we're spending too much money service the national debt to afford decent educational tools. Of course, it doesn't help that the "Educational" price for scientific instruments is often 2 to 3 times more than the "corporate" price - companies sucking at the government teat, of course.
"Superintendent Chalmers, thank you for your request for purchase of a time-domain reflectometer for use in your science classroom. While we value the ability of your students to perform valid and accurate experiments in physics, we've read somewhere on the Internet that a microwave oven will do just as well. They're about $50 a walmart. Therefore, your request is denied. Besides, I need a new Lexus. Sincerely, School Board"
Go ahead, mod me down, you know I'm right.
No, you are mistaken. The chemical being used in the experiment is 2,4-biphenyl-cho-cholate, a highly dangerous (yet tasty) organic compound known to cause sickness in household pets.
But I can understand why you might have thought they were talking about chocolate.
You can also measure the speed of light using ants, the ants are small enough that they can fit into the low energy points of the microwave.
If you put some ants in the microwave, and switch it on, they all start moving from the heat into the cold spots, measure the distance between the cold spots and you have the wavelength.
Obviously, you shouldn't *actually* try this, unless the ants happen to climb in there looking for food, then they're fair game :) And take the turntable out, that's cruel.
The calculation (chocolate or ants) does still rely on prior knowledge of the frequency of the microwave(s) being used. Trying to measure the speed of light without a prior fixed frequency or wavelength is much more taxing. A shortwave radio can help though, or a flashlight and a large telescope (bouncing signals off the moon)
He claims that with effort, you might produce the second harmonic on a guitar string.
Considering that it's common to use higher harmonics for tuning...
The second harmonic is useful for adjusting the bridge, to ensure that the 12th fret is actually at the exact middle of the vibrating part of the string.
If you're going to experiment with your microwave, these should be fun. http://www.amasci.com/weird/microexp.html
-- http://qdbii.pyoko.org - Quote Database II I can't look at the words "Windows XP" and not think that Micro
How will you prevent "stupid parents" from having guns in the future?
The way they measure the frequency of these things is based upon the speed of light.
Therefore, "measuring the speed of light" actually uses the speed of light to calculate the speed of light, in a pattern of circular reasoning.
So this experiment is invalid.
I learned this when I spoke to my father about this article, having seen it linked to on slashdot about a year ago.
The one difference is that last time it was Tacos. This time it's Hemos, in an interesting twist.
Correct Horse Battery Staple: 72 bits of entropy. Enter "Correct H" into google. When it generates the phrase, that's
One can calculate the speed of light in a microwave, yet it still can't make toast.
!@#$% whole-grain cereal. When I want fiber, I eat some wicker furniture. - G. Carlin
only if you pluck it at the 12th fret. plucking it in the normal strummin' area will result in quite a big pile of harmonics.
better yet, just rest your finger on the string, without pressing the string to the fretboard, directly over the [12th|7th|5th] fret, and pluck anywhere if you want to hear some harmonics.
A microwave oven is a resonant cavity, and the resonant frequencies for the modes (TE/TM) are given by
where A,B,C are the dimensions of the cavity and i,j,k are non-negative integers (not all zero) which specify the mode.
This experiment does not "measure" the speed of light. All this "experiment" does is tries to isolate out a specific mode (i = 2, j = k = 0) and verifies that the frequecy rating printed on the back of the oven corresponds to this mode (which is still a cool thing to do).
You see, the manufacturer already implicitly *used* the value of c above in designing the oven and calculating the value of the number printed on the back of it, so the "experiment" is not capable of making a (independent) measurement of c.
Lest you think I am nitpicking, this kind of problem plagues us physicists all the time!
Is it African or European chocolate we're using here ?
"In a proper physics experiment all the quantities that affect the result have to be measured. In this one the frequency of the microwaves is taken for granted"
This seems wrong to me. Experiments seek to measure the unknown using the known.
Why is it less valid to measure the frequency by looking at the back (another person has measured the frequency and marked it on the device) than it is valid to measure the distance by comparing to a ruler where another person has has measured a set of lengths and marked them on your stick of wood.
More generally - do you expect scientists to measure the speed of light and the charge of an electron for every experiment they perform? If c and e cannot be taken as known - how about Pi?
If science is about accumulating knowledge - it seems odd to throw it all away for each experiment...
VLC Remote for iPhone and Android
Absolutely worthless to anyone who bought a microwave in the last 2 years because they switched to a slightly modulating, slightly moving frequency emmiter which makes sure that it heats all of the food as quickly as possible instead of little hot spots. So basically, it melts everything at once in a new microwave. At least in a "good" new microwave.
*There's Klingons on the starboard bow, scrape em off Jim!*
Why measure something that you already know the measurement of? I don't get it.
186,282 miles per second
I have tried this before with thin notepaper (made wet to control heating). Does give very uniform spots.
--da
about.com spawn in the time it takes to read the short exposition on wavelength!
Silly Nerdy, we already know the speed of light is 300 bazillion millimeters per second. Microwaves are being underused when measuring such trivialities with gross imprecision (a wooden ruler ?!). Nuke-o-matics are much better used to make things burst and/or arc in wonderful patterns of color.
Now this guy should find a way to measure the 'evilness' of a CD by frying it a few minutes on high. Perhaps a relation could be drawn between the bright blue arcs and the sheer nauseous content of an AOL 6.0 disc.
-Billco, Fnarg.com
This is perfect! I've been looking for a way to write off my snack budget as R&D, and this is it!
You guys just saved me $20,000. Thanks.
You didn't measure the speed of light, you measure a wavelength. Unless you can show that you had some way to confirm the frequency of the light source that is not dependent on knowing the speed of light, then when you looked up the frequency of the light source you were effectively looking up the speed of light and using it to determine the speed of light. No wonder your answer came out close!
I'm an American. I love this country and the freedoms that we used to have.
You can test other fun scientific conjectures at home, free, fun, and easy:
... and much, much more!
1. Heisenberg's uncertainty principle:
"Where the F*ck are my F*cking car keys!?!?!?"
2. Schrodinger's classic experiment on Superposition:
"Heeeeere kitty kitty kitty..."
3. Tycho Brahe's INCREDIBLE exploding bladder!
Ed R.Zahurak
You know, oblivion keeps looking better every day.
Is it me or does this just measure the wavelength, and then use a number from the microwave label which already has "c" encoded into it? It seems a bit of a cheat.
--- Ban humanity.
You need an inverted soup bowel or something to give clearance over the turntable drive peg.
Look, I don't know what the hell you just said, but you're not allowed in my kitchen.
Dewey, you fool! Your decimal system has played right into my hands!
5,280 feet in a mile, or eight furlongs (a furrow's length, which is 220 yards, the distance a horse or ox can plough in before requiring a rest), but the mile is based on the stride of Roman soldiers (see recent discussions on this on usenet::comp.text.tex).
:(
There are 8 pints in a gallon, 2 pints in a quart and, surprise! four quarts in a gallon.
Metric is an impersonal, arbitrary system w/ little relation to human measure / experience.
For example, the point system which you were maligning, while 72 pts. to an inch is a recent phenomenon (Warnock innaugurated it when he created PostScript since he knew all fonts would have to be re-created), there were 12 pts. (72.27 in an inch) to a pica, and if one measures in picas exclusively, then divisions of a page block are easy and don't get down into fractions---by contrast European specifications often have irksome decimals in them which are a nuisance (and they only rarely use the ``Q'', (quarter of a millimeter, ``kyu'' in Japan) as a type measure, so type sizes still get specced in points!
Similarly, Farenheit happens to capture the human ability to differentiate temperature, but one can have two items, both at a given celsius temperature which will feel to be different temperatures 'cause that measure is coarser.
96 dpi as a screen measure was set up for similar reasons (to allow even sub-divisions). Sadly, few programs honour the Windows facility for user-definable screen dpi---all-too-many are Mac ports hard-wired for 72 dpi
William
Sphinx of black quartz, judge my vow.
We have a formula for waves that relates frequency, wavelength and wave speed. It is empirically tested; try it yourself if you like.
Now, as with any mathematical formula, if you know all but one of the values, you can calculate the remaining one. The original article suggests that you obtain the frequency (by looking on your microwave) and the wavelength (by measurement) and use that to calculate speed. However, the speed of light has been calculated, and the result is known to considerable (9 significant figures) accuracy. So, you can instead take the speed of light, the wavelength and calculate the frequency.
It is not, in either case, circular. You have a formula with three variables. You find and fix the values of two of them. You are therefore able to calculate the value of the third. If this concept eludes you I suggest you take a freshman algebra course. Circular reasoning (a concept explained in freshman philosophy courses) is where you have an argument where you attempt to prove one of the premises in your conclusion. This is not a case of that, this is a simple case of mathematics.
How can there be stable nodes in the electric field within the oven if the distance between the oven walls is not a whole multiples of a half-wavelegth? Aren't the dimensions of the cavity set so that multiple patterns of standing waves will co-exist, each with its own nodes?
1) The microwaves are lower energy waves than light. There's just "more" of them in that cavity than visible light from the appliance bulb.
2) Generally speaking, materials (esp. un-ionized gas) will have a lower refractive index as frequency decreases. Hence, microwaves will be slowed less so than visible light in the air cavity of the microwave.
3) The patterns formed in the chocolate are due to standing waves set up in the cavity. The chocolate is a thin layer at the bottom, so the nodes will not reflect standing waves set up INSIDE the chocolate, because the wavelength is too large. So the patterns reflect the wavelength of microwaves in air, which is negligably less than the speed of light in a vacuum.
Measurement error from the ruler is a much larger (orders of magnitude larger) factor here.
Fuck Beta. Fuck Dice
Wrong. The meter is defined by the distance from the Equator to the North Pole (divided 10 000 000).
No, it isn't. It really is defined from the distance travelled by light in one second. However, it was originally intended that there be 10,000 km from pole to equator: after performing the survey, the metre was defined by the length of a particular piece of metal. Unfortunately, their survey was not quite correct, and the actual distance (in terms of that piece of metal) from pole to equator was 10,002,090 m. The length definition changed in 1960 and then in 1983 to its present form. Likewise, although one cubic cm of water has a mass of one gram for most practical purposes, it is not formally defined as such.
There is no place like ~!
Check out how to make ball lightning in your microwave at /etc video show titled "Fun with High Voltage Electrical Discharges".
One of my students tried this last year with quite satisfactory results.
Somewhat, but the question is what you did to it afterwards. Did you let it recool? Or did you take it out?
Now I am not saying you should microwave water by itself in an unmoving tray or even a moving one for that matter,
No, you shouldn't, as you can certainly overheat the water as it has nothing to nucleate at and form vapor.
If you want to really get yourself hurt, try dropping some coffee creamer in previously-boiled (and then recooled) water that you heat in the nuker for some substantial time.
At first it was a little scary and you have to wonder what the temperature is going to be when you stop it..
Yes, you should. If it's anything over boiling, then the water's superheated and sensitive to shock or pretty much anything else. The microwave company probably won't give you decent info on this, btw.
-Looking for a job as a materials chemist or multivariat
...you saved me the trouble. ;)
-Looking for a job as a materials chemist or multivariat
This only works if you can stop the mechanism by which the microwaves are scattered around to make for even heating. If you have a turntable in the bottom of your microwave, then removed it might do the trick, but most microwave ovens have a rotating metal "fan" that is enclosed in the upper surface over the cooking cavity, and that metal fan spins to scatter the waves around -- think of it like a flashlight and a mirrored pinwheel. Hence no turntable is required.
I'm not aware of any way of disabling that "fan", although I suppose you could drill a tiny hole in the shroud and poke in something to stop the spin, a la stopping a grinding PC fan. But I personally am not terribly interested in poking a drill into a microwave oven ...
One simple rule for its versus it's
At what temperature? And is that pure water? A mix of isotopes that normally occurs in nature, or the most common 18H2O?
Ambiguities like this is why the metric system was changed from such standards many years ago.
-Looking for a job as a materials chemist or multivariat
http://www.google.com/search?hl=en&lr=&ie=UTF-8&oe =UTF-8&q=speed+of+light+in+miles+per+hour&btnG=Goo gle+Search
returns
"the speed of light = 670 616 629 miles per hour " ??
However, you won't be able to "see" it unless you suppress the odd-numbered harmonics. That's really what they're talking about. Although, the method they describe is somewhat stupid, and unnecessarily difficult. Actual guitar players play harmonics all the time, simply by touching the string lightly at the desired node before plucking. In this case, that would be over the twelfth fret, or half of the length of the string.
Some ovens have the fan-type stirrer you describe, but not all. Others solve the problem of hot and cold spots by putting a turntable at the bottom which rotates food in and out of the hot and cold spots.
The experiment is for an oven with a turntable. The article talks about taking the turntable out and putting the chocolate on something non-rotating.
The answer to your question about cavity size and standing waves is I Don't Know. In fact, I've wondered for a while why microwave oven designers don't use the same trick as recording studio architects, and make the walls non-parallel.
It's possible that they have to make the cooking cavity resonant in order for the magnetron to "see" the right kind of load on its output. But that shouldn't matter much as long as there's food absorbing the microwaves.
From the article: Thus: the wavelength is .6m x 2 = 0.12m
Uh, sorry, but 6 cm = .06 meters, not .6m
and .6 x 2 = 1.2, not 0.12
Lucky for you two wrongs make a right, so you got the right answer!
sometimes i likes to sits and thinks, and sometimes i just likes to sits
The article states, "The distance between the hot spots is half the wavelength of the microwaves..." which would only really be true for the 200 mode, if it existed. It doesn't; so the article is even more wrong.
Even in the simplest case, where just one mode is excited, one must remember that for each mode there are two possible polarisations.
This is not entirely correct either. If one of the i,j,k is zero, there is no choice left for the polarization. It is completely fixed by k dot E = 0 and kz=0.
In any case, I agree that it is unrealistic to presume that a conventional oven only excites a single mode. But my main point is more serious: you cannot independently *measure* the speed of light using this method at all.
Why not measure the speed of light without all these givens? Do it the way it was originally done: with a bunch of mirrors, or by looking at the moons of Jupiter, or any other way. These experiments which use high-tech devices with high-precision values already given, seem pretty damn pointless. It's like saying "Hey, I can use this complex computational algebra system to prove the correctness of the quadratic formula!" Gee, good for you...
Yum!?!
Why not both?
Just because you can, does not mean you should.
Forget chocolate. Use those microwavable poppadoms instead. You can see the standing waves clear as day when you heat those. They cook so quickly (30 seconds) that there is no time for conduction of heat through them. As a result the pattern of cooking directly reflects the microwave energy distribution.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
There is a page 1 to the article as well that gives some good historical background on measuring light speed.
how abuot the waves bouncing against the inner walls of the microwave? dont they cause inference with the wave just entering? the interference come in all directions and how is that able to have it 'in sync'... or all the nodes where it's supposed to be?
my blog
As far as easily thinking about the speed of light, english units are better.... It travels almost exactly one foot per nanosecond. This helps when imagining light streaming from a light bulb, or thinking about why ethernet can only go 300 feet. So amaze your friends by telling them they look 4 nanoseconds younger (when 4 feet away) than they actualy are.
-John Fenley
Ok, I read through the article, then tried to go to it again, and apparently it's a different article now. I had notices a glaring mathematical error in the first one, where he said
.6m x 2 = 0.12m
.6 to .06. Very odd. Editors that *gasp* edit!?
Thus: the wavelength is
And when I looked at it again, the whole page layout was changed, and it was changed from
This space for rent, inquire within.
ok... so get inverting then whats your point?
...almost exactly one foot
Dude, it either travels at EXACTLY one foot per nanosecond or it doesn't. There is no such thing as "almost exactly".
My car gets 40 rods to the hogshead & that's just the way I likes it!
I read about a trick on the web a few years ago so I tried it at home and showed my family. I cut a grape in half length-wize, but left a little skin connecting the halve, lay the two round sides on a plate, placed it in the microwave, hit start, and **ZAP!!!** -- flames, sparks, toasted grape halves flying apart.
My brother thought it was "awesome," my mom feared for her microwave, and my dad (an EE) said "ah, the grapes are about the size of the wavelength of a microwave so the grape must be acting as a dipole antenna, neat" and walked away.
Show here how to measure light with the chocolate she is just eating. What happens after is up to you ;)
He's right, and I've not seen it anywhere else listed here.
But the meter is defined by the speed of light now, and so there is no way to "measure the speed of light" unless you're doing it in something other than meters.
The only thing the SI community can do now is to more accurately measure the meter, not more accurately measure the speed of light.
I am unamerican, and proud of it!
Why wasn't the speed of light defined to be 3*10^8m when they were going to define meters by this speed anyway? I mean, it wouldn't have any practical implications other than beautifying some physical formulae (no big deal, I know, but still). Like, the intrinsic impedance of free space would be exactly 120*pi ohm instead of approximately 376.7303135 ohm!
Wrong. This is not true. The sun is exactly where it looks like it is, to within any reasonable visual precision. The reason is basically because the Sun is not really moving, the Earth is rotating.
If a plane passes overhead high enough that it takes 10 seconds for the sound to reach you, its sound will seem to come from a point where the plane was ten seconds ago. This is sometimes noticeable with fast jets flying low. This is a true observation because the plane is moving.
But suppose you faced away from the jet and then took 10 seconds to turn 180 degrees and be looking at the jet. Then the jet apparently swung around from behind you to in front of you over those 10 seconds. But the sound doesn't come from behind you. That's because the jet didn't really move from behind to in front of you in 10 seconds, it just looked like it did.
In the same way, the sun doesn't really move 4 widths in 8 minutes, it just looks like it does. The sun's actual motion relative to the earth is 360 degrees in 365 days, i.e. one revolution per year or about one degree per day. In 8 minutes the Sun moves only a tiny fraction of a degree.
Therefore when you look at the Sun, it is pretty much exactly where it looks like it is.
(Furthermore there is another factor called aberration which makes the visual effect even smaller.)
Just got done reading the article, my only question now is how exactly do we measure Light with modern techno advances to shave off the rust from 186k mpS to less of a rounded answer?
I want decimal points to be satisfied!
EOU
this isnt really measuring the speed of light, your just measuring a scaled version of it from whoever the person who claims the frequency
props to my hgh school history teacher!!11
An easier way to find out the speed of light is to get two MW radio receivers, one having its tuning scale in metres and the other in kilohertz. Tune the wavelength-labelled set into a station and write down its wavelength. Then, tune the frequency-labelled set into the same station and write down its frequency {which will be a multiple of 9kHz, by the way}. The product is the speed of light, with any multipliers still in effect {so if you multiply kHz by m, you will get km/sec}.
Or, you could ring up and ask the frequency in kHz and the wavelength in metres.
For example, before they went FM stereo,Radio Derby's old MW wavelength was 269m. Their MW frequency was 1116kHz. This gives c = 300204 km/s.
Je fume. Tu fumes. Nous fûmes!
Yeah, I forgot to mention that; we measured the frequency of the driving signal using a frequency counter.
Read the experiment again.. we measured the wavelength of the PULSES of light, not the light itself (Visible light has a very short wavelength, you can't measure it directly with a ruler)
The frequency of the light itself is irrelevent.
The frequency we were pulsing it at was low enough to be read electronically using a frequency counter.
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