Newton's Cradle microwaved

[snopes]

Comment: I was recently directed to, http://www.youtube.com/watch?v=Lkn6fMn9eqU . It is a video clip of the show Braniac wherein a Newton's Cradle is placed in a microwave, causing an explosion destroying the microwave. Common sense and my limited electrical engineering studies seem to tell me that that shouldn't happen. While it would undoubtedly spark quite a bit in the gaps between the balls, I am fairly confident that for significant destruction to occur, something would need to create a short circuit across the magnatron. Even still, it seems to me that there is nothing in a microwave that would combust in a manner seen in the video. Surely, the sparks created could start a fire, but I don't believe an explosion of that strength could occur. Any chance this video is doctored to promote some "fuzzy science"?

Seems a natural reaction to metal in a microwave, I've seen a microwave go up like that before with metal in it. It's the microwave itself combusting not the contents.

[Little Galaxy]

I'm not scientific enough to say exactly what should happen, but it doesn't seem right to me either. I can believe the innards could catch fire, but I can't believe that this would cause an explosion big enough to blow the panels off. As the OP said, what would be inside a microwave that would combust in that fashion?

What's got me scratching my head is the sparks (if there are any - the quality of the video makes it hard to tell if there are tiny sparks or just blips) - with that much metal in there shouldn't there be more? I've seen bigger sparks in a malfunctioning microwave that was heating a glass of water!

At least when the Mythbusters microwaved CDs you got to see some serious sparks!

[BluesScale]

The magnetron will be running on about a quarter amp at 2000 volts typically and is vacuum sealed. That is quite a bit of energy and I would expect a failure to be energetic as a result especially when the vacuum failed. If the capacitor went (likely in the case of a short) then it could explode with a fair bit of force. I had seen electolytics punch through a PC case.

I am fairly happy that this video is real

Blues

[Little Galaxy]

Something else is bugging me:

It seems that the first explosion blows the door open. Then the second rips it off its hinges. But once the door is open, wouldn't the second explosion just follow the path of least resistance? So it makes me think that the only way the door would fly off with that much force is if an explosive charge has been added.

[Troberg]

No way it's going to blow like that. Metal can cause the output stage to fail through overheating, but it's not that dramatic. Running a MW with a metal object in it is basically the same as running it empty (the metal don't absorb the waves, causing some of them to eventually bounce back into the transmitting antenna and overload i). Even so, what happens is that something melts, which can have two results:

1. A short circuit occurs, a few sparks fly and the fuse is blown.
2. The circuit is broken and it stops.

If it would fail that spectacularly when run empty, it would be outlawed.

Now, if you MW a leaking bottle of acetylene, well, that's a different story.

[hambubba]

The excess current generated by reflection off metal CAN travel to the grounded case... I have seen the plugs catch fire at the wall several times. This is more likely than the microwave itself catching fire or exploding.

(DRAT! I just threw one away last week! I should keep them for, you know, "experiments".)

[Spam & Cookies-mmm]

Originally Posted by hambubba

(DRAT! I just threw one away last week! I should keep them for, you know, "experiments".)

"We do these experiments so you don't have to."

(Champagne, beer, Christmas lights, a cd, a can of beans, steel wool, a lightbulb... all at the same time.)

[Troberg]

DRAT! I just threw one away last week! I should keep them for, you know, "experiments".

What?!?! You threw away a working microwave without experimenting with it until it wasn't working anymore?

You should at least have tried some harmless experiment, such as MWing a burning wooden stick. It creates some wonderful plasma balls.

I've always wanted to fill one up with neon (after sealing it) and then setting it at full blast. It should be harmless, but very spectacular.

[Beachlife!]

Originally Posted by Troberg

What?!?! You threw away a working microwave without experimenting with it until it wasn't working anymore?

You should at least have tried some harmless experiment, such as MWing a burning wooden stick. It creates some wonderful plasma balls.

I've always wanted to fill one up with neon (after sealing it) and then setting it at full blast. It should be harmless, but very spectacular.

Plasma balls are cool. The easiest way to create one is with a grape sliced in half. My daugher once inadvertanly created a large one with some ketchup packets.

[Fun with a 9mm]

Newton's Cradle?? Is THAT what that thing's called??

Originally Posted by Beachlife!

Plasma balls are cool. The easiest way to create one is with a grape sliced in half.

WOW! (I had to try it.) It was neat but why is it called a plasma ball?