Electricity from Water: How Does It Work?

[chound]

I have this clock which if u fill with water will start working! How dus it work

 

[Averagesupernova]

More details please.

 

[hitssquad]

This has more details:
http://www.realgoods.com/shop/shop3.cfm/dp/302/ts/4170301

• Water-Powered Clock or Calculator
  You won't ever have to buy any batteries or plug in any cords to use this LCD clock or calculator. Both work using nothing more than ordinary water. The secret is a patented revolution in fuel cell technology that harnesses the energy of water molecules to provide a futuristic stream of pollution-free electrical current. Just pull out the two tiny reservoir tubes from underneath the clock's sleek arch, fill them from your tap, and amazingly! you'll have enough power for two months of operation.

 

[Locrian]

Very amusing. New to me. If anyone has more details I'd be interested in the particulars.

 

[brewnog]

I had one of these once, though it used potatoes instead of water.

The water isn't the source of the power. The electricity is being produced by the difference in electrode potentials of the anode and the cathode which are inserted into the water (or potato). It's just a battery, it looks a little bit different, but the clock draws a very small amount of current anyway.

 

[russ_watters]

The water isn't the source of the power. The electricity is being produced by the difference in electrode potentials of the anode and the cathode which are inserted into the water (or potato). It's just a battery, it looks a little bit different, but the clock draws a very small amount of current anyway.

So its powered by a dissolving hunk of zinc? That was my guess too...

What happens when that is gone?

 

[brewnog]

Takes a while. My Potato Clock had (zinc and copper? maybe?) electrodes, they were probably about 4 grams each, and the only noticable change I could see was some slight surface corrosion on the zinc. I ran it for about a year before I got bored and took it to bits...

After a few weeks, it stops working, so you change the potatoes and it works again. Of course, this is just dehydration of the potatoes, but fraudsters will tell you it's because the potatoes are the power source.