When two diff erent metals (copper, galvanized steel, or aluminum) are inserted into a piece of fruit or a vegetable, a potential diff erence exists between them. A sensitive ammeter connected between...

When two diff erent metals (copper, galvanized steel, or aluminum) are inserted

into a piece of fruit or a vegetable, a potential diff erence exists between them. A sensitive ammeter connected between the electrodes will measure a current, although

not large enough to light a bulb. Th e fruit or vegetable acts as the electrolyte in this

battery. Try diff erent fruits and vegetables with combinations of electrodes. Th is is

the principle behind the commercial “two-potato clock.”