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Measure The Speed Of Light With Your Microwave

Posted by Hemos on 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. "

7 of 296 comments (clear)

  1. Kids... by JessLeah · · Score: 5, Funny

    ...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
    1. Re:Kids... by vofka · · Score: 5, Informative

      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.

      --
      Disclaimer: I meant what I thought, not what I wrote! What? You can't read my Mind? Oh dear!
  2. Measure The Speed Of... by Anonymous Coward · · Score: 5, Funny

    ...Your Local Fire Department by placing some metal in your microwave and putting a blanket over it. =P

  3. Measure the frequency of your microwave instead by boa13 · · Score: 5, Interesting

    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.

  4. Spoiler by kinnell · · Score: 5, Funny

    It's 3x10^8 m/s

    --
    If I seem short sighted, it is because I stand on the shoulders of midgets
    1. Re:Spoiler by Captain+Nitpick · · Score: 5, Funny
      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.)
      --
      But then again, I could be wrong.
  5. Ants by BuilderBob · · Score: 5, Funny

    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)