How to Make a Potato Powered Light Bulb

A little girl holding her hand over a lit light bulb, while laughing with her dad. — A potato is not only food; they can also emit low currents of electricity. Peter Cade / Getty Images

Did you know you could power a light bulb with a potato? The chemical reactions that take place between two dissimilar metals and the juices in the potato create a small amount of voltage that can power a very small electrical device [source: MadSci]. Follow the instructions below to make a potato-powered light bulb.

Materials:

A large potato
Two pennies
Two zinc-plated nails
Three pieces of copper wire
A very small light bulb or LED light

What you need to do:

Cut the potato in half, then cut a small slit into each half, large enough to slide a penny inside.
Wrap some copper wire around each penny a few times. Use a different piece of wire for each penny.
Stick the pennies in the slits you cut into the potato halves.
Wrap some of the third copper wire around one of the zinc-plated nails and stick the nail into one of the potato halves.
Take the wire connected to the penny in the half of potato with the nail and wrap some of it around the second nail. Stick that second nail into the other potato half.
When you connect the two loose ends of the copper wires to the light bulb or LED it will light up [source: MathinScience].

Be careful when handling the wires, because there is a small electric charge running through the wires. Hydrogen gas may also be a byproduct of the chemical reactions in the potato, so don't perform the experiment near open flames or strong sources of heat [source: MadSci].

Originally Published: Jun 2, 2011

Potato Battery FAQ

How does a potato battery work?

Potatoes contain acids, which start a reaction allowing electrons to flow between two metal points. The potato acts as a salt bridge that connects the anode and cathode, releasing salt ions to help generate electrical energy.

Can a potato light up a light bulb?

If you want to power high-voltage bulbs, then the answer is no. A potato battery generates roughly 0.5 volts of energy, which is only enough to light up a low-voltage LED.

Why does my potato battery not work?

Check your wires and connections. Use copper as an anode and zinc as a cathode. A lot of people use steel nails, which doesn’t work, so be sure you’re using a nail that is covered with zinc. Don’t connect loose wires to the electrodes. Instead, use alligator clips for a secure connection.

How many amps is a potato battery?

Potato batteries can produce about 0.2 milliamperes of current and 0.5 volts. However, you can increase the power by connecting a group of potatoes together in a series if you want more voltage.

Does boiling a potato increase its power?

Yes, researchers claim that you can increase the power output of a potato by boiling it for about eight minutes. Boiling breaks down the organic tissues inside potatoes and shrinks resistance, allowing electrons to flow more easily and generate more power.