Fun With a Microwave Oven!

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Basics of a Microwave Oven
The Classic CD-in-Microwave experiment
My Favorite: Paper Clip
Micro-fine Wire

Basics of a Microwave Oven

A microwave oven consists of a high voltage power supply, a microwave emitter (magnetron), a control circuit, and a tuned resonant cavity. This cavity, of course, is the area where you place your food when you want to heat it up. The food is heated by the microwaves, which cause water molecules in the food to twist around rapidly, thus producing heat. The microwaves that bombard the food are at a frequency of 2.54 GHz, which is close to a cellphone's frequency. At 2.54 GHz the waves are about 12cm long, and if you measure the inside of the microwave oven you will find that from one side to the other is a usually multiple of 12cm. On the door you will notce a metal mesh, this is to keep the microwaves from getting out. It reflects the microwaves, much as a mesh satellite dish reflects radio waves.

THIS IS IMPORTANT!!!! ALWAYS PLACE SOME WATER (IN A CUP OR FILM CAN) IN THE MICROWAVE OVEN WHEN DOING EXPERIMENTS TO ABSORB EXCESS MICROWAVE ENERGY! If you don't put water in the oven you risk overheating the magnetron and destroying the oven!

I suggest using 2 film canisters of water in the back corners of the microwave oven. I also recommend that you don't use the microwave oven in your kitchen for these experiments, but it's okay as long as you let any fumes out and clean debris from the interior of the microwave.

With this in mind, let's get on to the experiments!


The Classic CD-in-Microwave

Get a CD, preferably a blank recordable CD, but if you don't want to waste that you can use one of those free AOL/MSN CDs. Remember to put the water in the microwave oven first. Get a film can and put the CD on top of the film can in the microwave oven. It doesn't matter whether or not you have a turntable in the oven. Set it to 5 seconds (10 at most, after that the CD will melt and produce noxious fumes.) Turn it on. In seconds you will see a massive electrical discharge flash across the CD, burning tracks into the surface. When you take it out you will find that the CD has a pattern burned into it. How the patterns look depends on the CD you use.

For a more impressive show use several CDs, but make sure you separate them enough and always support them by the central clear area.

The Paper Clip in a Microwave

You will need sheet metal for this, if you don't have any, use a few layers of alumnium foil. Take your sheet metal and cut it into a 6 cm circle. This is your "artifical ground plane," a circle 1/2 wavelength in diameter. Then get a paper clip, preferably one of the large ones (not those huge ones that people use as bookmarks.)Bend it so that there is a "base" with an "antenna" sticking up.

Cut the antenna to 3cm, or 1/4 wavelength. Tape the antenna to the center of the 6cm circle, and put it in the microwave oven for 30 seconds.

You should hear a loud buzzing sound and the tip of the paperclip should flare up into a ball of flame that looks a bit like a sparkler. It will go dimmer or brighter as it moves around on the turntable.

The tip of the paperclip will melt into a glowing ball of molten metal after a while. When you take the things out of the microwave oven, it will be hot, so be careful.
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Micro-fine Wire

This experiment involves ectremely thin wire. Try 36AWG magnet wire or thinner. You can get it from:
--Microwave ovens with turntables (take apart the turntable drive motor)
--Radio Shack (maybe)
--Brigar Electronics (, get the 38AWG *magnet* wire or thinner.)
REMEMBER that higher number in AWG means thinner (i.e. 38AWG is thinner than 36AWG.)
Take some of it, form it into a mesh/coiled wire mess (works best), put it on a cermaic tile and microwave it. In moments there will be a HUGE burst of light from the microwave oven, and following that will be plasmoids ("ball lightning") rising from the flaming mess. It is truly an awesome spectacle. Be careful though as the insulation will burn off the wire, making fumes.

I'll have more soon, these are the ones I have tried and I think are cool.