A potato-powered clock demonstrates the conversion of chemical energy to electrical energy. Galvanized steel contains numerous metals, such as chromium, iron and zinc. The zinc in the nails and the copper in the wires used in a potato-powered clock prompt the transfer of electrons to the battery contacts in an LCD clock. The potato battery, which is an electrochemical battery, will power a small LCD clock or small light bulb for several seconds before the electrolytes in the potato are exhausted and the current ceases.
Remove the battery from the LCD clock and make a notation of which sides held the positive and negative contacts.
Mark the potatoes as No. 1 and No. 2 with a marker.
Insert a steel nail in the one side of each potato. Allow 1/4 of an inch of the nail to stick out of each potato.
Insert a 1-inch copper wire in each potato on the side opposite the nail. Allow 1/2 inch of the wire to stick out of the potato.
Attach one end of an alligator clip to the wire in potato N. 1 and the other end to the positive contact in the LCD clock.
Attach one end of another alligator clip to the nail in potato No. 2 and the other end to the negative contact in the LCD clock.
Attach one end of a third alligator clip to the nail in potato No. 1 and the other end to the copper wire in potato No. 2 and turn the clock on