Potato Light Bulb Experiment

The Seasons

(Physics for ages 8+)

If you’re looking for an exciting and boredom-busting activity, this just might be the one for you! Did you know you can use potatoes to light up a light bulb? It seems crazy, but there is electrical energy all around us and even in everyday things like the food we eat. The video above shows exactly how it’s done. Here’s what you’ll need:


Copper wire or copper nails
Iron-galvanized nails
Electrical wire (with or without alligator clips)
Light bulb
Voltmeter (optional)
Adult supervision (Adult supervision at all times please)


  1. Start by inserting a 3-inch piece of copper wire about half-way into each of your potatoes (use 2, 3, or more potatoes if you’d really like to ramp up the voltage and brightness of the light bulb).
  2. Next, insert an iron-galvanized nail half-way into each of your potatoes. For best results, try to insert the nails about an inch away from the copper wire pieces.
  3. If you are using thin electric wire without alligator clips, you will need to remove some of the plastic covering. Cut two 6-inch strips of wire per potato you are using (if you are using 2 potatoes you need 4 strips, 3 potatoes will need 6 strips, and so on). Have an adult help you remove about ½ inch of plastic covering from both ends of each of the wire strips.
  4. You will need to attach the wires to your nails to complete an electrical circuit. In doing this, it is important to note the copper wire is the positive terminal (like the positive end of a battery), and the iron nail is the negative terminal. If you are using wires with alligator clips, simply clip one end to the copper wire of potato 1, and the other end to the iron nail of potato 2. If you are starting with just one potato, clip one wire from the copper wire to the light bulb, and connect another wire to the iron nail and light bulb. If you are using wires without alligator clips, simply wrap the exposed ends of the wire around the tops of the iron nails and copper wire pieces.
  5. Complete your circuit by attaching a strip of wire from the positive terminal (copper wire) of one potato to the negative terminal (iron nail) of the next potato. When you are finished, the light bulb should be attached to the negative terminal of the first potato and to the positive terminal of the last potato in the series. Please see the video for clarification on building this circuit.
  6. If you have voltmeter, replace the light bulb with the test terminals of the voltmeter to test the voltage coursing through the potato circuit. Try starting with a small circuit of just one potato and work your way up to several potatoes, testing the voltage of each circuit. You can also try different types of potatoes to see which kind makes the most powerful circuit (for example: Russet versus Yukon gold).


A potato is made up of water, sugar, and acid. When certain metals, like the copper and galvanized iron, are inserted into it, they react and create a flow of electrically charged molecules to move from the negative terminal to the positive terminal.

This reaction also released hydrogen gas as the charged molecules move through the entire potato circuit. Each potato releases a certain voltage, so connecting them in a series increases the total voltage output, which in turn brightens the light bulb. What other kinds of food might work to create a “food battery?”