The potato clock
This is a rather odd name for a clock, yet it is an accurate description of its appearance (see Figure 4). It is actually a small quartz clock that is equipped with a liquid crystal display but that, very uncommonly, uses potatoes as its energy source. In actuality, it works using electricity as any other quartz clock but since it uses so little energy, the battery has been replaced by two potatoes! Two pairs of copper-zinc electrodes are inserted in each potato, offering a rather novel example of the Volta battery. It works as long as the potatoes remain moist. When they dry out, they can be replaced by another pair, as one would replace a spent battery. The potatoes have the advantage of not polluting the environment and can even be eaten!
