Potato Clock

Potato Clock
With a Potato Clock, you won't need batteries or electricity from the power socket anymore –(at least not to know what time it is).
Do you remember your first physics kit, which generated power from fruits, lighting up a small bulb? The Potato Clock works the same way, but instead of a small lamp, it supports a digital clock. The potato battery is classic, but you can use apples, lemons or beverages too to generate power.
The setting is simple, you just need to add two fresh potatoes or a fruit of your choice. Now attach the copper and zinc strips to the clock and the potato, using the cables, –and current will flow.
It's that simple! Copper and zinc have different redox potentials. That's why zinc releases electrons which move to the copper. This way, the metal stripes become minus and positive poles (electrodes). The potato works as the electrolyte, offering the conductive dilution. The formula gives the reaction: Cu2+ + Zn ? Cu + Zn2+.
In the end, you get a voltage of ca. 1 volt.
As well as the digital clock, the cables and the metal strips, there are two cups which could be used to build a battery out of salt water, lemon juice or other fluids.
By the way: you shouldn't eat the used fruit afterwards.