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How to Make a Potato Clock With Pennies

"One potato, two potato, three potato, four." You can use the word "potato" in counting games, but you can also use a real potato to keep time. An electrochemical battery, or cell, generates an electrical current by promoting and controlling the transfer of electrons. These electrons are the electrical current. When you power a digital clock with a potato battery, for example, the exchange of electrons between the potato battery's zinc electrodes and its copper, or penny, electrodes provides the power. Making a potato-powered clock is easy.

Things You'll Need

Potato
Knife
Dinner plate
3 six-inch pieces of copper wire
2 pennies
2 galvanized (zinc-coated) screws or roofing nails
Digital clock powered by one AA battery
Electrician's tape

Instructions

- 1
  Cut a potato in half using a knife and place each half of the potato on a plate with its cut side down. Arrange the potatoes so that one is on the left and one is on the right to make assembly easier.
- 2
  Wrap one end of a 6-inch piece of copper wire around a galvanized screw or roofing nail and push the point of the nail into the left side of potato on your left. You'll find galvanized (zinc-plated) screws or nails and copper wire at any hardware or home supply store.
- 3
  Wrap one end of a second 6-inch piece of copper wire around another galvanized screw or roofing nail and the other end of the wire around the middle of a penny. Cut a slit in the right side of the potato on your left with the knife and push the penny you have wrapped with wire into the slit. Push the galvanized screw or nail on the opposite end of the same wire into the right side of the potato on your right, forming a connection between the two potatoes.
- 4
  Wrap one end of a third 6-inch piece of copper wire around another penny. Cut a slit in the left side of the potato on your right with the knife and push the penny you have just wrapped with wire into the slit.
- 5
  Remove the AA battery from a digital clock.
- 6
  Touch the free end of the wire connected to the nail in the left side of the left potato of your potato battery to the battery contact on one side of the clock's battery compartment. At the same time, touch the free end of the wire connected to the penny in the left side of the right potato of your battery to the battery contact on the opposite side of the battery compartment.
- 7
  Observe the digital clock. Reverse the wires you are holding, touching them to opposite contacts in the battery compartment of the clock, if the clock doesn't work at first.
- 8
  Tape each wire end to its battery contact with electrician's tape when the clock is working.

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