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116 Making Things Move
Hydraulics is the technical name of the field concerned with creating movement from
compressing fluids, but is usually reserved for heavy machinery like bulldozers and
excavators. We’ll cover this a bit more in Chapter 6.
Bio-batteries: Creating Power from Food
You can make a battery out of any fruit or vegetable that’s acidic: potatoes (see
Figure 5-11), tomatoes, onions, lemons, oranges, and so on. A bio-battery functions
on the same basic principles as a traditional battery. When two strips of different
metals (typically copper and zinc) are inserted into an acid solution (in this case, the
acidic moisture inside the food), an electrochemical reaction takes place, which generates
a potential difference (voltage) between the metal pieces. In a bio-battery, you can use
a galvanized nail or other metal (zinc is the coating in anything galvanized) along with
FIGURE 5-11 Potato power (credit: Kaho Abe)
