A potato contains moisture and acid that react differently with two metals — copper and zinc, for example. That chemical reaction creates a small push that moves energy through the wire, the same way water pressure drives water through a hose. Wire enough potatoes in series and their voltages add together, producing enough current to light a low-power LED.

An LED needs very little current to glow. With the right combination, four potatoes wired together can produce enough current to light two low-power LEDs. That result shows how little energy an LED requires compared to a regular bulb.

Every battery stores energy through a chemical reaction between two different materials. A potato contains moisture and acid that can trigger this same reaction. Push two different metal strips — copper and zinc, for example — into a potato, connect a multimeter, and you can read the voltage each metal combination produces. Different pairs generate different amounts of power. Wire two or more potatoes in series and their voltages add together. With the right combination, four potatoes can produce enough current to light two low-power LEDs.

A potato's moisture and acid can drive a chemical reaction between two different metals, and that reaction generates a small voltage you can measure with a multimeter. Different metal combinations — such as copper and zinc — produce different amounts of power. When you wire multiple potatoes in series, their voltages add together. With the right combination, four potatoes can produce enough current to light two low-power LEDs.