By A.J. Andrews • Updated August 30, 2022
Using a potato as a power source is a classic demonstration of electrochemical cells. By inserting a zinc nail and a copper penny into the potato and connecting them to a small bulb, you can observe how chemical energy is converted into electrical energy and see approximately 1.5 volts of output.
Slice a large potato in half. In each half, cut a slit just wide enough to slide a penny. Place a zinc‑coated nail in the opposite slit. The potato’s natural electrolytes allow electrons to flow from zinc to copper.
Wrap a short piece of 16‑gauge copper wire around a penny. Place one wrapped penny in each potato half. Then wrap the remaining end of the wire around the zinc nail in the opposite half. Repeat with a third piece of wire for the second zinc nail.
Touch the free ends of the wires to the base of a small flashlight bulb, making sure the penny and nail wires do not touch each other. The potato should light the bulb for one to two minutes. After that, the electrodes undergo a chemical reaction that reduces electron flow, stopping the current.
Safety note: Handle knives carefully and keep the setup away from water to prevent short circuits.
