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Science

Measure The Speed Of Light With Your Microwave 296

Posted by Hemos from the godiva-or-hershey dept.
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. "
This discussion has been archived. No new comments can be posted.

Measure The Speed Of Light With Your Microwave More

Measure The Speed Of Light With Your Microwave

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  • Measuring the speed of light is easy (Score:3, Funny)

    by kfg ( 145172 ) on Monday September 29, 2003 @03:13AM (#7082686)
    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

  • Kids... (Score:5, Funny)

    by JessLeah ( 625838 ) on Monday September 29, 2003 @03:15AM (#7082694)
    ...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)

    • Re:Kids... (Score:3, Funny)

      by kfg ( 145172 )
      Gee. Thanks. Now I'm having a Cadbury Fruit & Nut fit.

      I have an Easter Bunny on my back.

      KFG

    • Re:Kids... (Score:5, Funny)

      by Citizen of Earth ( 569446 ) on Monday September 29, 2003 @04:19AM (#7082916)
      It is also highly addictive and should be used with extreme caution. Overdose can cause morbid obesity, sluggishness, and death.

      Yeah, well the guy put some dihydrogen monoxide (DHMO) [dhmo.org] into his microwave as well, so we know that he has no concern for his own safety or those around him!

      • Re:Kids... (Score:5, Informative)

        by fredrikj ( 629833 ) on Monday September 29, 2003 @05:39AM (#7083088) Homepage
        Water in microwaves can be quite dangerous though. Check out the "Coffee Explosion" part on this page [amasci.com].
        • Actually, no. I have been making some ad hoc inquiries into this matter with the help of the company microwave, a bunch of free pasta, and a mighty hunger.

          Now I am not saying you should microwave water by itself in an unmoving tray or even a moving one for that matter, but (though I think somewhat inferior to ordinary pasta cooking) it works fine if you put cook pasta as I have several times in a plastic microwave safe deep tray with about equal parts water and spaghetti. The starch that initially comes

        • Re:Kids... (Score:5, Informative)

          by vofka ( 572268 ) on Monday September 29, 2003 @07:40AM (#7083433) Journal
          Hmm, Well it's not entirely true to say that water doesn't boil in a Microwave oven - nor is it true to say that the container does not get hot.

          Think about it - Fill a (microwave save) plastic pint jug with cold water, and put the jug in your microwave for 5 minutes on full power. Now, is the water hot or cold? Is the jug hot or cold?

          Of course, the answer to both questions is "hot". The energy from the Microwaves heated the water, and the heat from the water conducted from the surface of the water to the surface of the container, heating the container.

          This heating of the container allows normal boiling to take place (as evidenced by the fact that the microwave will have been full of steam after heating a pint of water on full power for 5 minutes, and that during the heating time, the water can be clearly seen to bubble in the container!).

          While it is definately true to say that water does not boil in the same way in a Microwave oven as it does when boiled in a pan on the hob, it is definately not true to say that water does not boil at all in a Microwave.

          In fact, plain water is the best way of cleaning a Microwave Oven - a fact I have on good authority from my Dad, who services Microwave Ovens used in the catering industry. Simply place a pint of water in the Microwave on full power for 5 to 10 minutes, then carefully remove the jug from the oven, and wipe down the inside of the oven with a cloth.

          Not only does this method make it very easy to clean the cooking part of the oven, it also helps to clean the inner workings of the oven, in particular the fans and air ducting from the main cooking area.
  • According to the website, using the formula, the speed of light is 24 cubits per moonphase.
    • But how many rods to the hogshead is that?
      • Quite off topic.

        I was just sitting here, having finished RingTFA (first time for everything, ok?), and started looking through the posts to find something interesting to respond to, when I started laughing. and continued to laugh, probably for a good solid 5 minutes, getting louder whenever I came across a new insight...
        My SO finally got tired of the noise, stood behind me to see what was so funny; read for about 30 seconds, then she slapped me on the back of the head and said "you are very strange, you kn
  • 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

  • Hey how come mines slower ? (Score:2, Funny)

    by Anonymous Coward
    Is it just my microwave, or is the speed of light 2m/s ?

  • Got that beat (Score:5, Funny)

    by divide overflow ( 599608 ) on Monday September 29, 2003 @03:19AM (#7082712)
    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.

  • I DID IT! (Score:2, Funny)

    by Anonymous Coward
    Yay! I did that experiment! According to my calculations light in air travels at 783 km/h. Wow, that's fast!

  • Funny this should come up (Score:5, Informative)

    by Raul654 ( 453029 ) on Monday September 29, 2003 @03:24AM (#7082731) Homepage
    I was just writing a wikipedia page [wikipedia.org] 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.

    • Re:Funny this should come up (Score:3, Informative)

      by Anonymous Coward
      "This works rather well for sound, but never worked for light."

      Maybe that's because light is so amazingly fucking fast.

    • Re:Funny this should come up (Score:5, Informative)

      by zcat_NZ ( 267672 ) <zcat@wired.net.nz> on Monday September 29, 2003 @04:17AM (#7082913) Homepage
      We measured the speed of light by flashing an LED very rapidly (several MHz). The driving signal and the output from a photodiode were fed through equal-length coaxial feedlines into the X and Y inputs of an oscilloscope.

      The photodiode was moved away from the light source one full wavelength, at which point the image on the screen became a straight diagonal line again.

      I've also seen it done by bouncing a laser off a rapidly rotating octagonal mirror, across a room and back to the same mirror, but that one's a lot harder to set up correctly.

      • Re:Funny this should come up (Score:4, Interesting)

        by MillionthMonkey ( 240664 ) on Monday September 29, 2003 @04:53AM (#7083005)
        I did the rapidly rotating octagonal mirror experiment in college. I got 2x10^8 m/s which is pretty slow. Either the mirror speed was off, or between runs I might have jostled the paper on the wall with the pencil marks marking the beam position.

        You can measure the wavelength of light pretty easily with a ruler. But it has to be one of those shiny metal rulers, and it has to have black millimeter marks. Shine your laser onto the black marks at a shallow angle, measure the positions of the diffraction spikes that are reflected onto the wall, and from that, calculating the wavelength is trivial. It works pretty well.

        • If you are going to use a diffraction grating, then why dont you use a CD ? A CD makes a very good refraction grating (thats why you see a rainbow on its data side), and with those Yamaha Cd burners which you could use to draw pictures on the data side of a CD, it should be trivial to make a grating with the exact properties you want
          Anyway the point about this experiment was I think to measure the speed/wavelength of light as directly as possible without any complicated equations etc. If you are going to

      • Re:Funny this should come up - or maybe not (Score:4, Interesting)

        by frovingslosh ( 582462 ) on Monday September 29, 2003 @09:11AM (#7083872)
        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!

    • Re:Funny this should come up (Score:2, Informative)

      by Anonymous Coward
      This works rather well for sound, but never worked for light.

      Obviously. And it's not a large distance apart. It was less than a mile, if I'm not mistaken.

      As for the doing the experiment itself, each person had a covered latern, would uncover it, and then the other person would uncover his once he saw the light from the first person.

  • History of light speed measurement (Score:5, Informative)

    by ramk13 ( 570633 ) on Monday September 29, 2003 @03:24AM (#7082732)
    Short informative read:
    http://math.ucr.edu/home/baez/physics/Relativity/S peedOfLight/measure_c.html [ucr.edu]

  • Measure The Speed Of... (Score:5, Funny)

    by Anonymous Coward on Monday September 29, 2003 @03:24AM (#7082737)
    ...Your Local Fire Department by placing some metal in your microwave and putting a blanket over it. =P

  • This is boring (Score:3, Funny)

    by Anonymous Coward on Monday September 29, 2003 @03:24AM (#7082738)
    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.

  • The link to first page of the article.. (Score:3, Informative)

    by heytal ( 173090 ) <hetal.rach@gmaRASPil.com minus berry> on Monday September 29, 2003 @03:25AM (#7082739) Homepage
    [about.com]
    http://physics.about.com/library/weekly/aa012703 a. htm

    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

  • Half the experiment is missing (Score:5, Insightful)

    by panurge ( 573432 ) on Monday September 29, 2003 @03:34AM (#7082759)
    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, so it is not a proper experiment. Just reading the value off the label doesn;t count. All the experiment actually allows you to work out is the wavelength of the microwaves, which is not hugely interesting. So how do you measure the frequency?

    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?

    • Sure. As another poster suggested, just reverse the formula. We know the speed of light, to a high degree of accuracy. Therefore, you can use this same test to figure out the frequency of your microwave.

    • Re:Half the experiment is missing (Score:4, Insightful)

      by hughk ( 248126 ) on Monday September 29, 2003 @05:26AM (#7083067) Journal
      Cutting open a magnetron to check the cavity size works only if you have a spare! And in any case, the resonance of a Magnetron cavity depends directly on wavelngth and is only related to frequency by the speed of light (which you are trying to measure).

      The frequency will almost certainly be 2.45 GHz - a couple of other frequencies are allocated but aren't used much. The frequency isn't constant because the magnetron's operating frequency typically varies with temperature however for getting a 5% accuracy, it should be ok.

      One complication of measuring by beat frequency is that a magnetron is pulsed. The duty cycle allowing power control. The problem is that this may mess up any indirect measurements.

    • Speed of light should be the same as the speed of EM waves, if then there could be a way of measuring this. Just get a long enought network cable, keep varying the transmission frequency on the cable, 10 MB, 100 MB etc. till the echo effect starts affecting you.That distance should be something like the time taken for the reflected shound wave to be half a phase wrong. So you know the frequency, you know the cable length and hence you can calculate the speed of the EM wave in the cable.
      Any idea if this is
    • 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.
    • "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 mark

      • You should throw out the frequency measurement for the same reason that the experiment threw out the speed of light measurement.

        This thing isn't intended as an "experiment" anyways, it's just a cool thing to do with your microwave to demonstrate the nodes and troughs, and to understand how frequency, wavelength and the speed of light relate to one another.

        Of course it's silly.

  • Measure the frequency of your microwave instead (Score:5, Interesting)

    by boa13 ( 548222 ) on Monday September 29, 2003 @03:35AM (#7082764) Homepage Journal
    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.
    • actually, we know the speed of light exactly, because the meter was redefined to make c==2,99792458*10^8m/s
      • I've always wondered - if they were going to go through the hassle or "redefining" the meter to that number (path light travels in a vacuum over 1/299,792,458 of a second), why not just make it an even 1/300,000,000 of a second. That way the speed of light would be exactly 300,000 km/s and make everybody's math a little easier. Sure people would have to make minor changes to already-measured distances (and I'd assume that anything on Earth would be small enough to basically ignore the variation), but just
        • Well, the speed of light is 3.00e8 ms-1 to three sig figs, but when you bring in that fourth significant digit, it becomes 2.998. So, if you fudged the metre (or the second) to make the speed of light a 'round' 0.3 billion ms-1, you'd start getting noticeable effects to the left of the decimal point around the 1000-10000 metre range - kilometers, in other words. You'd end up changing the number of meters in a mile from about 1609 to about 1610, for example. But the effect would be there past the third signi
    • 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.

      Damn - are you telling me Nature won't be publishing the paper I submitted?
    • I always thought that there was a little thing that looked like a fan near the point where the magnetron connected to the oven and that its purpose was to change the geometry of the situation as it turned, so that no single standing wave pattern would cause uneven heating in the oven.

      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 sta

  • 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? : )

  • Melting "chocholate" and measuring c? (Score:5, Funny)

    by WIAKywbfatw ( 307557 ) on Monday September 29, 2003 @03:41AM (#7082785) Journal
    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.
    • 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.
  • ...marshmallows. [umd.edu]

    Maybe we can combine the methods, add graham crackers, and create C-smores!

  • Why bother measuring it? (Score:3, Insightful)

    by The Famous Druid ( 89404 ) on Monday September 29, 2003 @03:43AM (#7082798)
    The metre is defined in terms of the speed of light [wordreference.com], so by definition c=299792458 m/s

    Pretty pointless trying to measure it really.

    • Well, actually not. The definition is for speed of light in a vacuum. So you could (theoretically) use this to determine the speed of light in warm, chockolate-odor filled air, which will be lower than the speed in vacuum.

      And, if you already know the speed (or the refractive index) of warm air, and find out the index for chockolate, you can use this to determine how much of the chockolate actually precipitates into the air of the oven as it is heated. This all depends on a little more accurate measurement
    • 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 G

      • Nope... (Score:3, Informative)

        by dreadnougat ( 682974 )
        you're wrong, or at least outdated: http://lamar.colostate.edu/~hillger/meter.htm
      • 1 gram == one cube centimeter of water

        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.

    • Hmm, so a meter is then:

      One 299,792,458th of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.

      And we europeans sometimes say the inch system is weird. :-)
      • But, an inch is defined as .0254 times one 299,792,458th of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. I'd say that is even weirder.
        • Wrong. An inch is the width of George Bush's, or the currently elected leaders, thumb.
          Obviously, when Bill Clinton was in office, we had this VAST problem with his definition of a foot in relationship to this measure.

  • Spoiler (Score:5, Funny)

    by kinnell ( 607819 ) on Monday September 29, 2003 @03:45AM (#7082803)
    It's 3x10^8 m/s

    • Re:Spoiler (Score:2, Funny)

      by fruey ( 563914 )
      Even Google Calculator knows the speed of light

      the speed of light = 299 792 458 m/s

      You are wrong by 207 542 m/s which is quite a large margin for keeping the Slashdot correction nazis at bay.

      • Re:Spoiler (Score:5, Funny)

        by Captain Nitpick ( 16515 ) on Monday September 29, 2003 @06:02AM (#7083118)
        You are wrong by 207 542 m/s which is quite a large margin for keeping the Slashdot correction nazis at bay.

        On behalf of the Guild of Pedants and Correctors, I hereby state that a 0.0692% error is well within the acceptable error for most Slashdot posts.

        Quite frankly, we're usually happy if you people get within an order of magnitude of the correct value.

        (P.S. We really don't appreciate being called nazis. We may be fanatics, but we're not fascists.)
    • A better test is, how fast do pedantic slashdotters reply to you saying it's actually 299792458 m/s?

  • Calculation OK? (Score:3, Informative)

    by anagama ( 611277 ) <obamaisaneocon@nothingchanged.org> on Monday September 29, 2003 @03:49AM (#7082814) Homepage

    I'm no physicist but, seems to me, 6cm would be 0.06m, so more like 3 x 10^7 per solid Girardehli testing.
    • Anyway, the measured distance between the melted points from my sample was 6cm.

      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 .6m x 2 = 0.12m

      Then the speed is 0.12m x 2.5 x 10^9 /s = 3 x 10^8 m/s, which is a pretty good estimate! If you want to do better, you can try repeating the measurement many times (and making very accurate measurements) and applying statistics to get an average, and an estimate of how much uncertainty you have.

    • Re:Calculation OK? (Score:3, Informative)

      by carlmenezes ( 204187 )
      Yes, 6 cm is 0.06m.

      However look at the calculation. There is a counter-error which evens things up :

      0.6x2=0.12m which is wrong.

      The correct calculation is :
      0.06x2 = 0.12m.

      Anyway,
      0.12x2.5x10^9 = 3x10^8 is correct.

      So I think it's just a typo with a zero missing. The actual calculation IS correct.
    • Yeah you are right, but he made another mistake that canceled out the first one:

      Thus: the wavelength is .6m x 2 = 0.12m
      0.6m x 2 = 1.2m or
      0.06m x 2 = .12m

      So, had he done all his math right he would have gotten 3x10^8. As it is, his lab report will come back quite bloodied by the red marker.

  • I get more enjoyment... (Score:3, Funny)

    by Anonymous Coward on Monday September 29, 2003 @03:50AM (#7082819)

    ...out of trying to explain to the physics-challenged that microwaves are actually bigger than the little holes in the door screen.

    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...

  • 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} :-)

  • Blast my taste buds! (Score:4, Funny)

    by MoeMoe ( 659154 ) on Monday September 29, 2003 @04:16AM (#7082909)
    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?!

  • Using Ping to measure speed of light (Score:4, Funny)

    by AYeomans ( 322504 ) <ajv@nOspAm.yeomans.org.uk> on Monday September 29, 2003 @04:43AM (#7082982)
    You can always use your network cables instead; brief description [computerbits.com] or full paper [arxiv.org].

    Anyone care to use the method with RFC1149 Avian Carrier Protocol [faqs.org], namely Using Ping to determine Speed of Flight!

  • MST3K (Score:5, Funny)

    by NanoGator ( 522640 ) on Monday September 29, 2003 @04:48AM (#7082994) Homepage Journal
    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.
  • What's the velocity factor of chocolate?
  • usually dissapears at the speed of light anyway...

  • Google is up on this (Score:2, Interesting)

    by EmagGeek ( 574360 )
    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

  • Ants (Score:5, Funny)

    by BuilderBob ( 661749 ) on Monday September 29, 2003 @06:00AM (#7083114)

    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)

  • If you're going to experiment with your microwave, these should be fun. http://www.amasci.com/weird/microexp.html
  • First of all, let's not forget that the speed of light is a defined [lbl.gov] quantity:

    c=299,792,458 m/s (

    exactly).

    A microwave oven is a resonant cavity, and the resonant frequencies for the modes (TE/TM) are given by

    omega(i, j, k) = pi * c * sqrt( (i/A)^2 + (j/B)^2 + (k/C)^2 );

    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 spec

    • Exactly ..... this is why you can never really verify Ohm's law, since either a voltmeter actually measures the current flowing through a known resistance, or an ammeter actually measures the voltage developed across a known resistance, depending on how you think about it :-) Plus, depending how you set up the experiment, either the ammeter is going to be measuring not only the current through the test resistance, but also the current through the voltmeter; or, the voltmeter is going to be measuring the v

  • Very nice but.... (Score:2, Interesting)

    by Ceadda ( 625501 )
    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.
  • You can test other fun scientific conjectures at home, free, fun, and easy:

    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! ... and much, much more!

  • This won't work for most microwaves (Score:5, Insightful)

    by ChrisCampbell47 ( 181542 ) on Monday September 29, 2003 @10:20AM (#7084392)
    I'm surprised that nobody's posted this yet (or that that comment hasn't made it up above +2).

    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 ...

  • That's nothing, try using grapes (Score:3, Funny)

    by skintigh2 ( 456496 ) on Monday September 29, 2003 @04:10PM (#7087996)
    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.

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