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Old 04-18-2016, 10:06 PM
Machine Elf Machine Elf is offline
Join Date: Feb 2007
Location: Challenger Deep
Posts: 10,623
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.