Summer break is an excellent time to invigorate your science-loving family with some easy, at-home science projects for kids. And what’s cooler than building your own battery with common household materials?
Making a homemade battery is a fun, simple science experiment that teaches us about how a battery charges and discharges an electrical current. Like an alkaline battery that powers your flashlights or remote controls, this homemade battery needs three main things to convert chemical energy into electricity: a positive cathode, a negative anode and electrolytes to move ions between the two channels. Those moving ions generate an electrical charge.
Required materials to make a fruit battery:
- One medium to large tomato (green tomatoes work best)
- Kitchen knife and cutting board
- Two four-inch lengths of copper wire
- Two large metal paperclips (textured or non-shiny version)
- Two beakers or short drinking glasses
- Alligator clip leads
Okay, have everything ready? Let’s get started.
First you’re going to cut the tomato in small slices, and then place half of the chopped tomato (including the seeds and juice) in each beaker or short drinking glass. Next you want to smash the tomato pieces with a spoon until you have a pulpy, goopy mixture.
Once your acidic tomato base is ready, insert the copper wires and metal paper clips into each end of the both beakers. Double check that the two metals don’t touch, otherwise the experiment won’t work properly. These glasses of tomato pulp function just like a battery cell because it has the cathode (the copper), an anode (the paperclip) and an acidic ion base (the tomato slurry).
Now take the alligator clips and clip one wire lead to the zinc electrode (the paperclip) and another to the copper electrode (the copper wire) in both beakers. This draws the ions between the paperclip and the copper, which creates an electrical current.
After that’s all set up, put on the or just hold them near your ears. Then touch the loose ends of the alligator clips to the metal end of the headphone jack. Within a few seconds you should be able to hear a static crackle as electricity flows from the tomato pulp into the headphones, which then make the current audible.
How Does a Tomato Make Electricity?
The electricity you’re hearing is generated by a chemical reaction flowing between the acidic tomato pulp and the zinc paperclip. The zinc reacts with negatively-charged ions in the tomato acid, and then these negative electrons are pulled toward the positive-charged copper wire. The flow repeats itself until the electrons are used up and your new tomato battery loses its power.
This science experiment can also be performed with a potato or lemon, if you'd like a less messy option.