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Old 04-18-2016, 12:55 PM
blood63 blood63 is offline
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starting a fire with a lemon

This video is a hoax.
I am embarrassed that I was duped into trying it.
I did get me thinking about how this could actually work.
With the right number of lemons are/or the right metals, could I actually start a fire?
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Old 04-18-2016, 01:01 PM
Machine Elf Machine Elf is online now
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Yes, but you'll probably need a shitload of lemons and a shitload (each) of zinc and copper elecrodes. Each lemon one would serve as one battery cell capable of providing about 1 milliamp of current; you'd want to wire your lemons in parallel so as to provide a large current. Don't know how many amps is required to light off steel wool, but probably not much.
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Old 04-18-2016, 01:19 PM
engineer_comp_geek engineer_comp_geek is online now
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Sure. You'd need a lot of lemons.

The basic idea is there. The lemon battery is often demonstrated in basic science classes. All you need to make a battery is two dissimilar metals in an acidic electrolyte, so if you shove copper into one side of a lemon and zinc into the other, you've got a battery. It's a pretty weak battery, typically producing a bit less than a volt and current maybe around a milliamp or so. More surface area on your metal anode and cathode will give you more current.

Using steel wool to start a fire is also pretty well known. It is commonly done with 9 volt batteries. A 9 volt battery can put out a lot more current than a lemon battery though.

A table-top's worth of lemons tied in series-parallel strands should do the job easy enough.
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Old 04-18-2016, 01:28 PM
blood63 blood63 is offline
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Quote:
Originally Posted by engineer_comp_geek View Post
Sure. You'd need a lot of lemons.

The basic idea is there. The lemon battery is often demonstrated in basic science classes. All you need to make a battery is two dissimilar metals in an acidic electrolyte, so if you shove copper into one side of a lemon and zinc into the other, you've got a battery. It's a pretty weak battery, typically producing a bit less than a volt and current maybe around a milliamp or so. More surface area on your metal anode and cathode will give you more current.

Using steel wool to start a fire is also pretty well known. It is commonly done with 9 volt batteries. A 9 volt battery can put out a lot more current than a lemon battery though.

A table-top's worth of lemons tied in series-parallel strands should do the job easy enough.
Or, instead of buying 20 or so lemons, I could slice each lemon into sections. Another video states that the electrodes will corrode very quickly in the acid and that I only have a limited amount of time before the current drops. Is this true?
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Old 04-18-2016, 01:36 PM
engineer_comp_geek engineer_comp_geek is online now
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Originally Posted by blood63 View Post
Or, instead of buying 20 or so lemons, I could slice each lemon into sections. Another video states that the electrodes will corrode very quickly in the acid and that I only have a limited amount of time before the current drops. Is this true?
That's true, but remember, thin slices and thin electrodes equals less current.
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Old 04-18-2016, 02:11 PM
Quercus Quercus is online now
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Quote:
Originally Posted by blood63 View Post
Or, instead of buying 20 or so lemons, I could slice each lemon into sections. Another video states that the electrodes will corrode very quickly in the acid and that I only have a limited amount of time before the current drops. Is this true?
It's true, but I'm not sure what 'limited' means in this case. Remember, the lemon isn't really doing much; mostly it's just sitting there passing electrons from one electrode to another (I think the acid may help a little bit, but that's not the most important thing). The metal electrodes are actually undergoing chemical reactions and being consumed by the reactions. So, yeah, the more current you run the more the electrodes will get used up (just like a non-rechargeable battery).
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Old 04-18-2016, 03:21 PM
Qwakkeddup Qwakkeddup is offline
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Cave Johnson, inventor of the combustible lemon.
  #8  
Old 04-18-2016, 03:53 PM
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extending beyond the steel wool, you could certainly use a few lemons and therefor a few milliamps to ignite a fire with other common materials. Several ignitable liquids which vaporize readily at low temperatures would require almost no ignition energy.

It's a bit less of a party trick given the inherent combustibility of these other materials, but if we can think of a substance with low ignition energy requirements that isn't commonly viewed as combustible we might have a useful party trick!

Perhaps you could use it to set off a mini explosion with sugar as the explosive agent?
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Old 04-18-2016, 04:09 PM
Lucas Jackson Lucas Jackson is offline
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Wouldn't a Bic lighter be easier to carry than a lemon and all those nails in a northern survival situation?

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Old 04-18-2016, 04:10 PM
Blue Blistering Barnacle Blue Blistering Barnacle is offline
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extending beyond the steel wool, you could certainly use a few lemons and therefor a few milliamps to ignite a fire with other common materials. Several ignitable liquids which vaporize readily at low temperatures would require almost no ignition energy.

It's a bit less of a party trick given the inherent combustibility of these other materials, but if we can think of a substance with low ignition energy requirements that isn't commonly viewed as combustible we might have a useful party trick!

Perhaps you could use it to set off a mini explosion with sugar as the explosive agent?
The oil sprayed out when you squeeze an orange peel is combustible- maybe something could be MacGyver-ed from a lemon rind?
  #11  
Old 04-18-2016, 04:13 PM
excavating (for a mind) excavating (for a mind) is offline
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I am curious why the OP thinks the video is a hoax and why subsequent posters think you would need a crapton of lemons. In the video, he uses 6 cells, stating it would produce "about 5 volts". As has been noted, it isn't only the voltage, but the amps that are important, but the amperage does not depend on the number of lemons, but the surface area of your electrodes. The brass paper brads he uses for the copper electrodes do have a lot of surface area.

If anything was "hoaxed" in the video, my bet would be that he injected a bit of HCl and water into the lemon just to make sure he had enough acidic electrolyte, but I am not sure that would even be necessary. He does squash the lemon a bit to make sure there is free flow of the electrolyte and cautions against letting the electrodes touch one another. I would really like someone explain why you would need a table full of lemons.
  #12  
Old 04-18-2016, 04:24 PM
engineer_comp_geek engineer_comp_geek is online now
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I haven't actually tried it myself, but my gut feeling is that the electrodes in the video are too small to produce enough current to heat up the steel wool to the point of creating flames. We're talking milliamps at about 4 or 5 volts, which ain't a whole lot of heat power.
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Old 04-18-2016, 04:32 PM
Chronos Chronos is offline
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The biggest issue I can see with the demonstration in the video is that you need the steel wool to be the highest-resistance part of the circuit. But with the cells wired together with wires just loosely hooked onto the electrodes, I don't expect that's likely to be the case.
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Old 04-18-2016, 04:47 PM
Count Blucher Count Blucher is offline
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Last edited by Count Blucher; 04-18-2016 at 04:49 PM. Reason: Oh Sh-t, this is GQ. Nevermind.
  #15  
Old 04-18-2016, 05:18 PM
blood63 blood63 is offline
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Quote:
Originally Posted by excavating (for a mind) View Post
I am curious why the OP thinks the video is a hoax and why subsequent posters think you would need a crapton of lemons. In the video, he uses 6 cells, stating it would produce "about 5 volts". As has been noted, it isn't only the voltage, but the amps that are important, but the amperage does not depend on the number of lemons, but the surface area of your electrodes. The brass paper brads he uses for the copper electrodes do have a lot of surface area.

If anything was "hoaxed" in the video, my bet would be that he injected a bit of HCl and water into the lemon just to make sure he had enough acidic electrolyte, but I am not sure that would even be necessary. He does squash the lemon a bit to make sure there is free flow of the electrolyte and cautions against letting the electrodes touch one another. I would really like someone explain why you would need a table full of lemons.
There is no way he produced six cells from a single lemon. How is he directing the charges inside the lemon? That is a single. The other electrodes are for show. Look how bright the steel wool gets. That's not possible.
I'm the OP, the one that got duped. I tested the voltages with my multimeter. A single electrode pair creates about 1 volt. Lining them up like they are in the video still makes one volt. It was fun to try and to play around with but there was no way it was going to work.
  #16  
Old 04-18-2016, 09:51 PM
Walken After Midnight Walken After Midnight is offline
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Recent related thread: I burned my lower lip with lemon.
  #17  
Old 04-18-2016, 10:08 PM
Walken After Midnight Walken After Midnight is offline
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They covered something similar on the programme Q.I., describing the use of lasagna to generate the electricity to power a gherkin lightbulb.
  #18  
Old 04-18-2016, 11:06 PM
Machine Elf Machine Elf is online now
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Originally Posted by excavating (for a mind) View Post
The brass paper brads he uses for the copper electrodes do have a lot of surface area.
But the zinc nails (which are probably just galvanized steel) didn't have much area. You're right, it might be possible to do it with one lemon if you use a shitload of each electrode type so as to achieve high metal surfacea area, but it won't happen the way he wired it. He's created a single 0.7-volt cell between the two end electrodes that he attached his circuit wires to; all the intermediate electrodes aren't going to participate, and the two electrodes that do participate don't have much surface area, so the current capacity will be very limited.

If you used a bunch of each electrode type in one lemon, you'd need to connect all of the copper ones together to serve as one single electrode with large surface area; likewise with all the zinc nails. That would give you a single cell with about 0.7 volts and a decent current capacity.

It may be that 0.7 volts can't drive enough current through the steel wool, in which case you'll need to create another lemon cell just like the one above. Wire it in series with the first so you get 1.4 volts. still can't drive enough current? Add another cell. Keep at it until you have the voltage you need to get the steel wool hot enough to light; it's certainly less than 9 volts, and ISTR even doing it with a 6-volt lantern battery.

TL,DR: if you use electrodes with enough surface area in each lemon, it may be possible to do this with 12 lemons or less.
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Old 04-18-2016, 11:11 PM
Senegoid Senegoid is offline
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Originally Posted by Walken After Midnight View Post
Recent related thread: I burned my lower lip with lemon.
He might have mixed in some fresh field-ripened pineapple juice. You can use that for rocket fuel too.
  #20  
Old 04-19-2016, 01:43 PM
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When life gives you lemons, start a fire.
  #21  
Old 04-19-2016, 02:55 PM
Really Not All That Bright Really Not All That Bright is online now
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Wouldn't a Bic lighter be easier to carry than a lemon and all those nails in a northern survival situation?
Yeah, but the lighter won't save you from scurvy.
  #22  
Old 04-20-2016, 07:36 PM
Irishman Irishman is offline
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There is no way he produced six cells from a single lemon. How is he directing the charges inside the lemon? That is a single. The other electrodes are for show.
Correct. In order to make multiple cells out of one lemon, you need to isolate each pair of electrodes, i.e. slice the lemon. That way, the wires cross between slices.

The way it is shown, there is no way the series connected electrodes are contributing to the charge. With what is shown, each wired pair is a closed circuit.
  #23  
Old 04-21-2016, 07:09 AM
Blue Blistering Barnacle Blue Blistering Barnacle is offline
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Correct. In order to make multiple cells out of one lemon, you need to isolate each pair of electrodes, i.e. slice the lemon. That way, the wires cross between slices.



The way it is shown, there is no way the series connected electrodes are contributing to the charge. With what is shown, each wired pair is a closed circuit.

So, and I think this was stated upthread, if you take the same configuration as in the photo, drop the wires (and the attempt to link in series) you could connect the in parallel and get more current (with greater metal surface area) but low voltage. You could wire up several similar lemons in series to step up the voltage.
  #24  
Old 04-21-2016, 07:13 AM
Blue Blistering Barnacle Blue Blistering Barnacle is offline
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I wonder if some distance would effectively isolate the nail pairs. Like, could you wire up nail pairs on opposite sides of a watermelon in series and get a step-up in voltage, or will the electrons "see" the nails on the other side of the melon.
  #25  
Old 04-21-2016, 07:41 AM
Terminus Est Terminus Est is offline
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Rather than try to build a battery, it would probably be easier to squeeze the juice out of the lemon then use said juice to focus the sun's rays on some kindling.
  #26  
Old 04-21-2016, 08:15 AM
DesertDog DesertDog is offline
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MRE heaters use a powdered iron and magnesium alloy in salt water to create jillions of short-circuited galvanic cells that according to Wiki generate about 50 kilojoules. Having used them, I can attest they emit a strong ozone smell; any hydrogen is undetectable. It would be difficult to harness that to ignite steel wool, though.
  #27  
Old 04-21-2016, 09:18 AM
Leo Bloom Leo Bloom is offline
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How would additionally sugar and water affect the conduction? The lemon has some of one and a lot of the other. When life gives you lemons, then make lemonade, then fire.
  #28  
Old 04-21-2016, 09:29 AM
Chronos Chronos is offline
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Quote:
Quoth Blue Blistering Barnacle:

I wonder if some distance would effectively isolate the nail pairs. Like, could you wire up nail pairs on opposite sides of a watermelon in series and get a step-up in voltage, or will the electrons "see" the nails on the other side of the melon.
Some, sure, but not very effectively. You'd need the internal resistance of the intervening fruit to be greater than the resistance of the rest of your circuit.
  #29  
Old 04-21-2016, 09:35 AM
Blue Blistering Barnacle Blue Blistering Barnacle is offline
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Maybe I'll try it as a summer science project once kids are out of school.
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Old 04-21-2016, 09:48 AM
Saint Cad Saint Cad is online now
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OK here's what I don't get about the video. Why is he wiring the zinc nails to the copper brads? What purpose is that supposed to serve?
  #31  
Old 04-21-2016, 10:06 AM
Blue Blistering Barnacle Blue Blistering Barnacle is offline
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OK here's what I don't get about the video. Why is he wiring the zinc nails to the copper brads? What purpose is that supposed to serve?

It's supposed to create a "series" of cells to step up the voltage (voltaic pile). But others have pointed out upthread that this will not be effective (because the cells are not isolated from each other). This video is felt to be a hoax by OP (who says he tried the experiment). Other posters agree for theoretical reasons.
  #32  
Old 09-10-2016, 09:04 PM
Blue Blistering Barnacle Blue Blistering Barnacle is offline
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Still thinking of selling this idea as science project to my boy.
  #33  
Old 09-10-2016, 09:17 PM
LunarPlexus LunarPlexus is offline
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Does the Samsung Galaxy Note 7 qualify as a lemon yet?
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Old 09-10-2016, 09:36 PM
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After reading the comments, but before watching the video, I was wondering if the different segments of the lemon would offer any sort of isolating effect. But, the brads and nails aren't even going in the right direction in the demo for that.
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