Do Microwaves come in different colours?

I'm guessing your metal bits are connected to the metal walls of the oven, which also do not sparkle when the microwave is on.

I'm guessing your metal bits are connected to the metal walls of the oven, which also do not sparkle when the microwave is on.

Well, yes, but the enamelled metal is by its very nature insulated by the glazing, an insulating glass. The whole affair is counter-intuitive... but I share the kitchen with forty other people, and if I test the oven to destruction I will not be popular!

I won't pretend to understand µwaves - if fact I've spent my whole professional life trying not to understand them, but I don't think electromagnetic radiation is stopped by enamel, or glass - which is why there is that thin metal screen in the window that keeps your eyes from cooking. I'm guessing that the metal walls form a cavity of some sort that is grounded and completes the circuit from the resonator.

If I add the terms "Smith chart", and "wave guide", I'll have exhausted my entire knowledge of the subject.

I had always assumed that the small-mesh screen in the glass door, by having holes smaller than the wavelength of the µ-waves, acted as would any Faraday cage, and stopped the passage of the electromagnetic energy. Your eyes don't cook (this would be most unpleasant, with them coagulating like grilled fish eyes) and so it must work.

Wave guides, I can understand; Smith charts I will have to read about...

Microwaves are rather long wavelength electromagnetic waves. To metal, they basically look like an oscillating electric field. Now color, as we percieve it, is variations in the wavelength of visible light. In that sense, yes there are different wavelengths (colors) of microwaves. As you can see on the chart below, microwaves simply refer to a range of wavelengths in the electromagnetic spectrum. That said, all microwaves are long enough to cause conducting in metal, therfore, either your metal thing in the microwave is grounded, or it's not metal at all, but plastic. At least thats my opinion.

ps. I like your avatar. At first I thought it was a spider, which I wouldn't have liked, since I hate spiders, but then I saw it had six legs. Makes all the difference.

That Avatar...is Doryphore, and no, he's not a spider, but a fine example of the Colorado beetle,

Leptinotarsa Decemlineata.

Not only has he six legs, but, as his name would suggest, ten stripes. This one is made in 3D using Blender.

The Colorado beetle is not a favourite amongst the potato-growing classes, and in Ireland we would often see posters, in post-offices and Garda Siochana barracks -

"Wanted, Dead or Alive! Have you seen this insect? - Squash him and send him to the department of Ag. in a matchbox, etc..."

Over the years Doryphore (the French name for him) became a bit of a folk hero to us, a kind of chrysomelidelian Robin Hood - all he ever does is eat spuds, yet everyone is after his head...

Still reading up on Smith charts. This might take a while...

Can it be that the thin layers of metal, as glaze or foil, intercept enough radiation to heat them as they are broad, but thin, so they spark etc.

The prongs are a bulk metal and would not heat that way. In fact metal inside the microwave will just be a reflector in most cases. Has anyone tried a large spanner for 10 seconds, as a test. Then increase time, feel it in the mean time to see it if heats.

In the UK there use to be a 10 pound bounty of colorado potato beetles...people began breeding them

Hmm! ...thought it was a tick.

Roger writes: "Microwaves are rather long wavelength electromagnetic waves. To metal, they basically look like an oscillating electric field."

Actually, EM waves interact directly with metals through visible-light wavelengths and beyond. It is the interaction of the EM wave's electric and magnetic components with conduction-band electrons in metals that make metals look shiny in the particular way metals do (metals essentially re-radiate the light!). Dielectrics (insulators) can look shiny, too, but not in the same way and not for the same reasons as metals. Here the shininess is due to mismatched impedances as the EM waves travel from one material (air) into the next (Pyrex®, say).

High-power lasers (esp. when focused) vaporize materials because of the extremely high electric fields produced by coherent EM waves. It is the coherence of laser light that makes it so effective as a cutting tool over, say, white light in which the frequencies and phases of the EM waves are essentially random. White light is incoherent as most light is. With monochromatic, coherent laser light the electric and magnetic components of each photon are in lock-step, like foot soldiers all marching together (and why they do not do so when crossing bridges). The field strength of each photon adds to the total, producing phenomenally high field strengths. The electric fields produced by high-power lasers literally tear the atoms in the material from each other. Molecules are completely disassociated. As the energy of the light is transferred to the material, this action plus absorption of the light results in a very hot, expanding plasma.

As for microwaves being short, I'd say that all depends on the basis for the comparison. If you compare microwave wavelengths to, say, VLF wavelengths, microwaves are tiny. To gamma rays microwave wavelengths are huge. But microwaves are called, well, micro waves! My guess from a historical perspective is that, when the term was coined, the basis for comparison was probably HF radio wavelengths.

And to answer the original poster's question, microwaves do, in fact, come in different colors! But I am thankful they don't make those awful Avacado Green or the Harvest Gold ones anymore. Ugh! Those colors are just soooo yesterday.

-e

Hahahaha. Funny. You could probably pick one up at a yard or garage sale.

I hate to be the bearer of bad news - but those awful retro-70's colors are coming back!

My microwave uses metal accessories as its a combination oven and grill.

The reason why the supplied accessories don't spark is simply that they are designed to distribute and build up of the field strength throughout the metal and so therefore the field is never large enough to cause a breakdown of the air dielectric i.e. to spark.

If you look closely, you will see that sharp edges are kept to a minimum and are round in shape. there are no points or sharp edges where the elecric field can build up sufficiently to create a discharge...

If you don't belive me put a piece of aluminium foil in and start the microwave, it will spark furiously!!

Any microwave will accept metal utensils inside the cavity as long as the metal has no sharp edges or points to concentrate the field and cause a breakdown...

The gold printing on a cup's decoration is extremely thin, so the metal has a sharp edge to it that will concentrate the field and lead to breakdown of the air...

I found this out by using my old microwave with the new microwaves metal accessories, and a bit of googling of course!!

John.

You know what, this is ringing a bell. I think I've heard this before. I bet he's right, that the metal is ok as long as its rounded and thick.

Roger, sorry to sound so immodest, but I am right!

that's why the metal utensils are round and not square etc... they form a deflector in the cavity and any charge build up hasn't the field strength to cause a breakdown of the dielectric (the air) to cause a spark...

As I said if you put a small piece of foil on the metal grill accessory then that will have the sharp edges to create spectacular sparking and of course massive loading on the magnetron... so not recommended!

John.

and not too close to the cavity walls.

I am not by any means knowledgeable in this; but I will give my 2.5 cents anyhow.

I think that the metal in microwaves is not really metal. Most are alloys or as stated by others grounded to the circuit. Metals when bombarded by the waves have a greater reaction than liquids since metal is more dense, like me! The metal gets hotter and such, molecular motion and all that. Plus the electro part in there too. All in all I think that I will personally stick to CDs and the like for my ten second light shows.

Just what the world needs, more disinformation.... thanks

What happens when you put a CD in a microwave? and, is that your eye?

Try it Steve and let us know eh??

John

John,

I like my microwave. Its 10 years old. Makes good popcorn. I think I'll keep it for a little while longer.

Steve

"I am not by any means knowledgeable in this"
- obviously

"I think that the metal in microwaves is not really metal"
- OK, now I know you jest...for a minute there I thought you were actually posting something serious...

"Most are alloys"
- which would make them, let's see...'metals'

"or as stated by others grounded to the circuit"
- when was the last time you saw a bonding conductor hanging from the metal chicken-holder, or the metal rack on which you place your plate in a combo-oven? And where would you plug it in to complete the 'grounded circuit'?

"Metals when bombarded by the waves have a greater reaction than liquids"
- No, liquids have a MUCH greater reaction, that's why moist foods heat quickly and easily, but dry foods do not. Try putting a piece of fresh white bread in together with a crouton and a nickel, then hit it for about 20 seconds - see which one is a hot, soggy mess.

"since metal is more dense, like me!"
- OK, not to get personal, but here we can agree

"The metal gets hotter and such, molecular motion and all that. Plus the electro part in there too."
- "Truly, you have a dizzying intellect" (Princess Bride, 1987)

"All in all I think that I will personally stick to CDs and the like for my ten second light shows."

- Great idea...but have you actually tried putting your CDs in the Microwave? I'm not sure my wife would appreciate me experimenting with hers, but let post a few pics and share the fun!

By the way - please don't take this response as an affront, it was just too much fun to pass up poking fun at...

A blank CD would be better I suppose...

Don't use a blank CD. Think how much more fun it would be to pick a CD with music that would complement the fizzes, sparkles, and pops!

uhhh...?

Au contraire. Just about the only part that isn't metal is the keypad, handle, eject cover and and exterior "cosmetix" as well as the film covering the inside cavity...and the plate turner. When sparking burns thru the cavity cover, then you will see the "actual" cavity material...sheet metal...sometimes rusty sheet metal to boot.

An intense sparking, sparkling multi-colored light shower results from microwaving a CD...just remember to remove it from the wallet cover etc...first...

I bet the burnt plastic smells good..

To quote from a well known film...

"I love the smell of burning plastic in the morning..."

John.

Surf's Up! (just watch for the bullets)

Microwave a clear glass light bulb. Doesn't matter whether the bulb actually works or not. The trace krypton gas they put inside light bulbs (to cut down on filament evaporation, presumably) puts on quite a light show when ionized by microwaves. Just be sure to zap the bulb for only a few seconds at a time (and to eliminate having to futz with the time setting, just set the time to around a minute, press Start, watch the show for a few seconds and then open the door to kill it). The bulb gets very hot and will actually melt if zapped for too long. My guess is that the tenuous-but-colorful plasma inside the bulb is extremely hot, and the krypton ions bombard the interior of the bulb at very high velocities, heating it.

I've never once harmed a microwave oven doing this.

On a different note, have you ever seen those blinky accessories for cell phones? Particularly the transparent battery packs that feature a bunch of LEDs that blink while you're talking? These packs make great microwave leakage detectors. You don't need a cell phone to use them in this way, as the battery pack's LED circuitry detects the RF independently. Just move the pack around the microwave - especially the door front and seals - and if the pack starts blinking, you've got RF leakage. Be aware that some packs, once triggered, blink for a preset interval before shutting off.

-e

Ooowwww that's a handy tip....

No not about the light bulb but those flashing rf detectors...

John.

Of course, those blinky battery packs don't tell you anything about the intensity of the leakage; just that it's strong enough to trigger the pack's detector. Makes you wonder if your cell phone is slowly baking your head while you talk! (Blonde bimbo trophy wives on their daily pilgrimage to Neiman Marcus seem especially vulnerable to this effect, by the way.)

You might also move your blinky pack around the computer to see how effectively it radiates RF. If your computer features an external WiFi transceiver, you'll need to unplug it first before doing your tests. As my notebook's WiFi transceiver is internal, I'm sure it would swamp RF emissions from the computer itself.

-e

Easier than a blinking telephone wotsit is the neon "Phase Tester" screwdriver that we probably all have... it will glow if the door seals leak, at which point it is best to throw the oven away. professional testers are sold which consist of no more than this, but in a fancy package at a fancy price...

I had one of those at one point, but I don't know where it is now. It would be interesting to see if one would respond to a cellphone. The RF field has to be pretty strong to ionize that neon, and so I'd say that if my microwave oven leaked badly enough to light the thing up, I'd sure as heck get rid of the oven (or take the door off, jimmy the switch, and place it face down on fire-ant nests to bake the buggers in-situ. It's been done.)

The nice thing about those blinky packs is that they seem to be pretty sensitive to levels of RF that are probably too low to light one of those screwdrivers. They're more useful, I think, to see what's emitting RF and what probably isn't. I suspect the RF detector in them is just some kind of high-speed diode suited for the purpose.

-e

...or take the door off, jimmy the switch, and place it face down on fire-ant nests...

We cleared a new "no-digging" vegetable plot in this way, by drawing a face-down, doorless oven (with suitable unauthorised modifications) slowly along the ground. Ten metres of cable and the inverse-square law must have given a safe distance from the operator. I was uncomfortable about it at first, for we as well as the weeds and their seeds, we surely also killed all the beasties and and Nitrogen-fixing bacteria in the soil... But then, when you heat plant-pots to sterilise them this happens too. Within minutes all the vegetation had keeled over and died. I don't know if this qualifies as "Organic Gardening", but no chemicals were used, and precious little electricity... Perhaps bacteria deep in the ground would survive, and re-populate the surface layers. Objective experimentation is needed - but I know already that you can sterilise plastic plant pots and their contents in this way, impossible in a conventional autoclave.

HEY!!!!!!!

You've just come up with the solution for my back gardening woes!!

Over the years I've left it for nature to look after... She's not done a very good job, according to my neighbours!

So nuking the garden seems ideal... Wonder if I could fit a horn to the magnetron output and use it safely pointed out the window?!!

I don't want to get wet now do I?

John

Wow! Great idea! What do the HSE think ?

Maybe if anything went wrong (like zapping an endangered species of worm) they'd fine the manufacturer for not putting an appropriate warning the the User Manual.