Looking for a fun and educational way to entertain the kids for a while? Got some extra potatoes laying around? We have the answer! The 'potato battery' or 'potato powered light' is a classic science experiment for teaching kids about the basics of electricity and how wires allow electricity to move from one place to another in a complete circuit.
You gotta love food science. And who knows? This science experiment could even get you out of a sticky situation someday. You may remember that the potato light was a life saver for Tink in the book Scaredy Bat and the Haunted Movie Set. So without further ado, let's create a potato powered light, Tink style!
Ingredients:
- 3-4 potatoes
- Two pennies/coins
- Two zinc-plated nails
- Three pieces of copper wire (with or without alligator clips)
- Small light bulb or LED light
- Grownup Supervision
Warning:
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
Instructions:
Start with two potatoes to see if they can turn on the light. If not, then experimentation is the key...
- Insert a coin and the end of one piece of copper wire into the potato so that they are pressed together inside the potato
- Wrap the loose end of the wire around one of the nails and insert it into the other potato
- Push a nail into the potato with the coin in it and wrap the end of a piece of wire around the top of the nail
- Insert a coin and the end of one piece of copper wire into the potato that has no coin in it
- Connect the two loose ends of the wires to the light bulb and watch it light up!
Tips:
- If you are using thin electric wire without alligator clips, you will need to remove some of the plastic covering.
- If the light doesn’t turn on, try turning the light around the other way (LEDS are polarized). If it still doesn’t work then try a different light.
- If it STILL doesn’t light up you may not have enough voltage. So you can try cutting the potatoes in half and adding in more coins and nails to make the circuit bigger.
- If you have a voltmeter, replace the light bulb with the test terminals of the voltmeter to test the voltage coursing through the potato circuit. Start with a small circuit of just one or two potatoes 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.
The Science:
We all know that electricity is what makes a light bulb work, right? The crazy thing is that there is electrical energy all around us, even in the food we eat. This experiment is leveraging that electrical energy. Here's how it works...
A potato contains sugar, water and acid. Certain types of metals – especially copper and zinc – react with the potato when they are inserted inside.
The copper and zinc have chemical energy. The zinc is more reactive than the copper so it wants to take electrons from the copper. In other words, the metals become electrodes, one positive and the other negative, and electrons flow between the metals. The potato acts as an electrolyte, which means it enables the electrons to flow through it.
When the nail and pennies are connected to a potato in a circuit, the chemical energy is converted to electrical energy.
You can tap into the electricity by connecting wires from the electrodes to a light bulb to form a circuit. The electrons flow from the positive electrode to the light bulb and back to the negative electrode. The electrical current passing through the light bulb is enough to make it light up.
What other kinds of food might work to create a battery? Perhaps a lemon?
Happy experimenting!