Am 15.09.2011 11:09, schrieb Invisible:

>  From that description, it sounds like zinc itself contains energy.
> Which raises a few questions:
>
> 1. Why do you need a fruit at all? Why can't you just extract the energy
> from the zinc?
>
> 2. Why does the other electrode need to be copper? If the energy comes
> from the zinc, surely *any* metal will do?
>
> 3. Why does using a potato work, but using a glass of water doesn't?

2. In layman's terms, the other electrode needs to be some metal that 
"contains less energy" than zinc (and should be a good conductor, 
comparatively inexpensive, and maybe meet a few less obvious constraints 
of the experiment)

1. + 3. You need a medium between the two electrodes that is a poor 
conductor for electrons (otherwise they would just migrate via that 
medium rather than the wire and load), but easily provides for free ions 
(otherwise the electron flow through the wire would quickly cease due to 
buildup of an electrostatic potential). Lemons and potatoes are quite 
good at this, while plain water isn't. (Battery acid is even better, but 
poorly suited to let children toy around with.)

Post a reply to this message