By David Dunning | Updated Mar 24, 2022
Begin by gently squeezing a lemon or lime to release its juices without damaging the skin. Insert a 2‑inch copper nail and a 2‑inch galvanized (zinc) nail into the fruit, spacing them about two inches apart and ensuring they do not touch to avoid a short circuit.
Inside the fruit, positively charged ions react with the zinc in the galvanized nail, freeing electrons. These electrons flow from the zinc (negative terminal) through a copper wire—secured with crocodile clips—to the copper nail (positive terminal). The resulting electric current, though modest, is sufficient to power a light‑emitting diode.
An LED typically needs only 2.5 to 3 volts and a current in the milliamps (mA) range—often a few thousandths of an amp—to illuminate.
