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Calculating the Speed of Light


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I did it with my microwave. its leet.

 

First, I got the frequency of the microwave from the data label inside:

 

f=2.45Ghz

 

We know that :nu: = f:lclambda:

 

So all we need to be able to find the :nu: of microwaves is the wavelength.

 

For this, I spread marshmellows out on a rubber plate. Then, I removed the tray in the microwave (so that the plate doesn't spin). When the marshmellows melt, you can see a distinct wave pattern in the melting. Measuring the distance between melted and unmelted marshmellows will yield our wavelength (actually, half of the wavelength).

 

I measured 2.4 inches as the distance.

 

Converted to meters thats .06096m. Since thats half the wavelength, multiply by 2. :lclambda: = 0.12192m

 

Now we have :lclambda:, and we can calculate :nu: of the microwaves...

 

:nu: = f * :lclambda:

:nu: = 2.45e9 s^-1 * 0.12192m

:nu: = 2.98e8 m/s

 

i rule :)

 

(btw, i found this experiment on the net)

dsc00006 copy.jpg

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Neat experiment :)

works good outside the MW cavity too, and use egg albumen instead, gives a better definition to the "hot zones" :)

Anyone know where ya can buy cheap sun screen? factor 1 million(ish) should do the trick :)

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A few year ago, I stripped appart a working MW oven and rebuilt inside a metal biscuit tin, the mw antenna stuck out the side of it and I made a conical wave guide from a large coffee tin and plumbers solder.

it transmits these MWs into free space, or whatever you aim it at.

we tried it out in a mates scrap yard, used an extension lead (about 20 meters) and hid behind the hood of an old car.

1`st test was a jar of popcorn, then varios bits of fruit and veg (even did a dog poop). eventualy after playing, I did the egg white thing, it worked well :)

 

I destroyed in the end because I accidently took out the neigbors hi-fi with it :( they never knew it was me, but I thought I`de play safe and get rid of it.

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Thanks YT, blike probably has plenty of scrap microwaves from past experiments and now you give him something else to play with.

I guess we'll be reading about mysterious fires breaking out all over his campus.

I still like the visual demos of physics so we gotta make sure blike doesnt blow himself up.

Just aman

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YT2095 said in post #15 :

I destroyed in the end because I accidently took out the neigbors hi-fi with it :( they never knew it was me, but I thought I`de play safe and get rid of it.

 

Accidently !!?!! LOL

 

Maybe there was a reason after all why you weren't allowed to put metal in a microwave ;)

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In actual fact putting metal into a MW pressents no problems at all, in fact I often do it, esp tin foil around the tails of fish so that they don`t burn. there IS however a way TO and a way NOT to do it. thin metal plating as decorations around cups/sauvers etc... will burn off, also any metal inside that touches the inside of the MW cavity or comes within a few Cms will ARC and . but other than that, it`s perfectly safe, boil a mug of water but leave the spoon in, you`ll see what I mean, it also helps prevent the "hot spots" that cause the water to boil over when you add coffee or sugar after, micro cavities of super heated water are more dificult to form with a metal spoon in :)

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The electrons inside the metal are flying around big time (more than usual) due to the large forces on it. But if you can make sure that the electrons can't arc by keeping a large distance between the metal and any of the 6sides of the microwave you are fine.

 

I would still advice never to use metal though.A microwave is made to heat water not to induces current in a spoon.

(only if you know what you are doing you can do it, otherwise never)

 

Edit:

This is something for your lightning thread if the metal that you put in your MW has sharp edges then it will have a much bigger chance that it will arc.

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regarding the last part of your post, it is indeed true, it`s also a major cause of leakage in many HT caps and circuits, more rounded nodes however can act as capacitors for charge in HT oscilators hence the use of domes in van de graff generators or Toroids in Tesla coils :)

 

and yes, you right also about the 1`st part...KIDDIES, DO NOT TRY THIS AT HOME WITH YOUR MOMS MICROWAVE!!!

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In the Pop Sci archives a guy shows how he puts lead in a ceramic bowl on top of whetstone bricks and the heat from the stones melts the lead. He melted tin also but could only get silver to radiant hot.

Just aman

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silvers one of if not THE best conductor of heat anyway, so it would be dispersing it quite well, it`s certainly the best electrical conductor (as a general rule the conduction of heat and electricity tend to go both hand in hand).

now if he`de have melted Tungsten, I`de be well impressed :)

lead and tin are the eutetic mixture (usualy 60/40) in solder also.

if he had any Antimony, that would have melted quite nicely too :)

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