There's a number of videos on this activity that you can find through Google. Unfortunately, given the nature of video, they often vanish mysteriously into the bit bucket. And you can't give them a 20-second "look over" to refresh your knowledge; usually you have to sit there through the whole production.
So here's about making batteries from unusual things.
* it takes some sort of acid in solution. You might be able to do it with unusual things like aspirin diluted in water because (according to internet sources... we all know how reliable those are...) UNbuffered aspirin can be used to temporarily "revitalize" a dead battery. I'll try it sometime. Meanwhile, other things you can make batteries from (in case you forgot to buy a potato for the demonstration) include vinegar, lemon juice, and cola.
* you need an electrode of copper and one of zinc. A nail (zinc coated) and copper wire (or a penny) work well for this. You could use silver instead of copper, but that's more expensive.
* make sure the "leads" are clean. A little scrub with an abrasive works.
* if you're not using a vegetable or fruit, get a small container for the liquid.
* the amounts of electricity produced are small.
* use them to power a small LED. Look for one (Fry's) that doesn't require a lot of voltage.
http://www.physics.gla.ac.uk/~kskeldon/PubSci/exhibits/E1/
http://hilaroad.com/camp/projects/lemon/calculator/calculator_battery.html
If you think you've got kids who may have seen potato/lemon/tomato batteries before, provide them with a little novelty. Using oranges or cola (or unbuffered aspirin if it works) will provide the "say WHAT?" factor that keeps them intrigued.
You will connect the battery components in series, not parallel, if you want to try and power a light:
http://www.sierranevadaairstreams.org/owners-guide/understanding/battery-config.html
http://www.zbattery.com/Connecting-Batteries-in-Series-or-Parallel
Monday, June 22, 2009
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