Re: edible battery to power clock

Brian,

No problem, Brian!  What you might like to know is that the type of 
vegetable/fruit/whatever has little to do with the operation of potato 
clocks.  What is important is the ELECTRODES (metal pieces) which are 
inserted into the respective vegetable matter.  (I'll bet you guys are 
using copper and galvanized (zinc-coated) nails).

The vegetable you use needs to be fairly gooey (like a zucchini or 
cucumber).  The liquid in the vegetable is an electrolyte, which means it 
has water with salt ions in it.  This allows something called an internal 
circuit to flow which in turn allows electrons (electricity) to flow 
through the wires and power your clock.  

Your teacher will no doubt want you to FIND out for yourself what 
vegetable works best.  So tell your mom to go out and buy a bunch of 
vegetables and experiment!  However, most vegetables should work.

Be careful which one you choose though.  The title says "edible 
batteries"...you just may have to eat your creation!

Tim Oborn
Chemistry Teacher- Calgary, Canada