So I get this video sent to me that looks legit except for a couple lame spots. Guy puts a 10p nail into the base of a thick table candle. Does the same for a second one. Then, very lightly strokes a disc magnet against each nail for about two seconds. Then, attaches an alligator clip and wire to each nail and connects the other end of each wire to a little flashlight bulb. Lights the candles and the bulb goes on. Blows the candles out and the bulb goes out. Does the trick with a little 3 v DC motor, too. Now, I guess I can believe that a flame could be responsible for the separation of charges of some of the materials that are involved, although I’m not totally sure how, but that doesn’t seem to be enough to generate a charge at all. And what’s up with the little stroking of the nails? Anyone familiar with this? I taught science for a lot of years and never came across anything like this. Scam? Straight Dope?
It’s a complete fake. I’m not sure if the video I’ve seen is the one you’re talking about, but in the one I’ve seen the power is being fed by a battery under the table. The candles and stroking the nails with the magnet are complete distraction, they do nothing.
There are any number of stupid fake videos like this - charge your iPod using an onion, etc. meh.
I haven’t seen this video, but back in the 1960s World Book encyclopedia had handouts on how to build a thermopile from differing wires arranged around a central point at which you placed a candle. You lit the candle and you produced enough potential difference to light a small bulb, so the basic idea of candle heat to electric power isn’t ludicrous. It’s not clear from my reading of your description if the one in the video was put together properly, though.
Here’s a plausible YouTube video of the idea:
There’s a site that looks as if it addresses the video the OP talks about, but I can’t get it to open:
This is the video (or at least one of a couple of versions available), and yes, it’s bullshit. The lack of descriptors in the parts list at the start suggest that these are “ordinary” candles and nails.
Most candles (including their wicks) will not conduct electricity, even if the nails penetrate all the way to the wick (which they clearly don’t).
Although combustion can produce electrically conductive ions that can complete an electrical circuit, it doesn’t particularly generate any voltage potential. In other words, neither candle flame would be expected to be at elevated voltage, or to cause an elevated voltage in the circuit if the flame were somehow part of the circuit (see previous paragraph).
Contrary to my wording in the above paragraph, the video does not show a complete circuit. There is an air gap between the two candles. If this thing works, then electrical charge is piling up at one candle, or electricity is somehow being conducted across the air gap between the two candles. The former would result in a nice electrical arc; the latter implies that candles have electrical capacitance, which they don’t.
Even if the candle flames did produce a voltage, both candles would be producing the same voltage, resulting in zero voltage differential across the test bulb/motor. Yet the video shows light or motor activity when both candles are lit, and no light/motor activity when only one bulb is lit.
The bulb achieves full brightness in a fraction of a second (as if a switch is flipped) after the second candle is lit, despite the fact that the wick’s flame ranges from almost nothing to full-burn over the course of several seconds.
Any others?
If you are going to make a fake like this, at least use a foot switch so that we don’t see you reaching under the table with your left hand to turn things on and off. 
Peltier devices, a Stirling engine connected to a generator, and the thermopile (already mentioned by CalMeacham) can be used to generate electricity from the heat of a candle. Real physics is a lot more fun than fake junior grade magic tricks.
So what could be under the table that could power up a light or a motor like that?
A cold fusion reactor.
a 2-gigawatt nuclear power plant.
Or a coal power plant.
Or a Honda portable generator.
Or a battery.
Pretty much anything, since it’s out of view of the camera.
You’re being intentionally misleading. It’s a cold fusion reactor with a 10p nail stuck through it. You stroke the nail with a magnet a few times, then connect alligator clips to the nail and attach them to the hidden wires that connect to the nail in the phony candle generator.
Note that there’s a cut in the video. It’s not continuous. The video cuts to a closeup of him “magnetizing” the nail in the candle. When it cuts back to the “original” view, it’s not really the original view. The position of the table with respect to the camera is slightly different. In other words, it’s not one long piece of video with a close-up cut into the middle of it. It is three distinct sections of video.
In the third section of video (after the close-up) note that the candles do not move at all on the table. Even when he connects the wires to the candles, he doesn’t move or rotate the candles in any way. He either has wires coming out the back side of the candles that he is trying to keep hidden, or the candles have been nailed into place through the table. If the candles are nailed into place, then the nails in the front are specifically placed so that they physically touch the nails coming up through the table. Either way, there’s an electrical connection that goes to the underside of the table.
Underneath the table he has some sort of power supply. It could be batteries or it could be a wall-wart type of power supply. He also probably has a switch. You can tell it’s a switch because his left hand goes under the table to turn it on and off, but his hand does not move around much when he does so. If he were connecting a 9 volt battery clip or twisting wires together, I’d expect his hand to move around more than it does.
I’ve never seen a video about onion power, but if it’s anything like a ‘potato/apple/whatever battery’ then it’s a very different thing than the candles with a hidden generator or battery under the table. You can actually run a light bulb (and I suppose charge and iPod) using a potato in the circuit, so the video might not be faked at all, though it could well be misleading if it’s saying the potato is actually doing anything.
If you use electrodes of two different metals, you can indeed get voltage and current across a potato, apple, or other things maybe including an onion. But the food has nothing to do with what’s going on, and could be replaced with a glass of saltwater with no change to the electrical power. In all cases, what’s going on is that the two electrodes are reacting with each other, gradually getting used up and creating electricity along the way, which is exactly what happens in a traditional non-rechargable flashlight battery. The apple is just conducting ions, and isn’t contributing anything to the reaction; as I said, it could be replaced with salt water, or the electrode paste inside a conventional battery.
The onion power one is made by an idiot who goes by the name of Household Hacker, who likes to post fake videos along these lines. In the video, he soaks an onion in gatorade (while mumbling some star-trek quality techno-babble about “electrolytes”) then plugs a USB cable straight into the onion. :rolleyes:
He has similarly poor quality fakes all over youtube, like how to power a TV from a AAA battery by basically connecting it to the AC plug :rolleyes: For a while he was a merciless spammer on the mythbusters message boards, and by pretending to be numerous people interested in his videos he managed to hoax the mythbusters producers into having Grant do a web only video debunking the onion video.
I guess some folks don’t mind being a moron as long as it gets them some attention.
You can actually make a battery out of an onion (or a potato, but personally I’d recommend a lemon since they work the best out of your typical fruity style batteries). All you need are two dissimilar metals, like copper and zinc (a penny and a dime, if you are wondering where you might get some cheap samples of these metals). Car batteries happen to use lead and lead oxide, but a lot of different metals will work.
Householdhacker’s “battery” is missing both the anode and the cathode (the two metals) so all he has is the electrolyte. Even if you do make a proper onion battery, it won’t have enough voltage or current to charge an ipod. You can probably get it to light an LED though. The more surface area your metals have the more current you can get out of your fruit battery, so using something larger than a penny and a dime will give you better results. You’ll still probably need a good plate full of onions to get something strong enough to charge an ipod.
Another way you can make your own battery is to take pennies and dimes (or pennies and nickels if you prefer) and stack them, alternating penny dime penny dime etc. with pieces of paper towel in between them. Once you have your stack, soak it in salt water.
You can measure some voltage difference between just about any two spots anywhere that aren’t connected by a good conductor. There’s no end to the possibilities. A multimeter may not be sensitive enough, but attach oscilloscope leads to random objects and you will see a DC voltage or even AC noise or waveforms. Free energy guys get fooled (or fool others) by doing this all the time. But you are measuring microvolts and seeing perturbations that could be caused by the wind.
I did see a report of what was basically a nail stuck in a tree, and a steady voltage difference relative to ground was seen. ‘Supposably’ MIT scientists claim the pH difference between the tree and the soil create this effect. Even though there is little voltage or current, everyone wonders what would happen if a whole forest were wired up this way. I’m guessing there’s insufficient current to overcome the resistance of all the wire needed. Maybe if the forest was on a treadmill…
I don’t doubt that this video is a fake, but the idea of creating electricity from a candle isn’t as far fetched as it sounds. It’s possible to use the heat from a candle to power a thermocouple, which generates electricity from a heat source.
This page here has some plans describing how to make a simple candle powered radio, and whilst the results probably aren’t spectacular the principle does work.
They do it for the revenue sharing income on the videos. Back in the day when Metacafe was paying good money for any video once it passed 100K views (and now on other sites that pay), it was crammed with videos like this, and they would try to spam techy blogs with them and announce them as ‘amazing science experiment’ etc.
Peltier modules from CPU coolers can easily put out several volts. Be careful though, since they’re made from Indium low-temp solder alloy, and are easily destroyed at quite a low temperature. If you wanted to drive one of these with a flame, you’d need to heatsink the hell out of the “cold” side, and possibly water-cool it.
I think Metacafe was killed by “clickmonkeys,” i.e. hundreds of thousands of botnet zombied machines masquerading as browsers viewing the site. It’s easier money than being a spammer! But legit advertisers will abandon your service if all their ad traffic comes from fake humans. Unless Metacafe had really good algorithms, probably most of those viewcounts were wildly inflated by bots. I’d noticed strange things going on with Metacafe views and became suspicious. Towards the end I saw a new user in “science” who posted some completely mundane video which attracted 100Ks views in a day or two. Then their view viewcount froze. It sat there for weeks, then the account disappeared. Hmmm. I imagined that Metacafe was desperately trying to hide this problem. What if some of their most famous producers were actually using botnets? (That would explain much.) I suspect that Youtube and Google developed way better sw for detecting which ad-clicks and vid-views are actually generated by bots.
They played it pretty close to their chest - and would never divulge exactly what (in terms of variability of source or duration of view) what constituted a ‘view’ (as well they might), but I think they just defined an unworkable business model - I think they were just hoping that most of their content would generate just under 100K views within the time limit - so they would get to keep all of the ad revenue, while the hopeful producers did all the promotion work. They just ate through their investment capital before they started turning a profit.
In the end, it was clear they had no money left and were making pathetic excuses (I had a video that attained 100K views within about four months, but they refused to pay me, arguing that it was too close to the (six month) limit.