This week we’re going old-school with the classic, science fair lemon battery experiment. As a child, my dad taught me how to make a lemon battery for a school project and so I thought it would be fun to carry on this tradition with Lexi.
Admittedly we did it the easy way with a kit that I bought, however, it is super easy to do with just a few, inexpensive items.
How To Make A Lemon Battery
- A lemon
- 18 gauge copper wire
- Wire stripper / cutter
- A small galvanized nail (i.e. covered with zinc)
- As a grownup to cut a piece of copper wire and strip off the plastic insulation.
- Roll the lemon on a table to get it nice and juicy.
- Stick the nail about 2cm into the lemon, then stick the copper wire in next to it.
- Make sure your tongue is moist with spit. Touch your tongue to the copper wire. Do you notice anything?
- Now touch your tongue to both the nail and the copper wire. What do you notice now?
- Attach a voltmeter and you will see some current.
Why Is There An Electric Current?
The tingle or metal taste you noticed shows that your lemon battery was generating an electric current. That means tiny electrons were moving across the surface of your tongue. Electrons are subatomic particles that zoom around an atom’s center and make up the part of the atom that is negatively charged.
The lemon battery you made is a type of battery called a voltaic battery. These types of batteries are made of two different metals, which act as electrodes, or places where electrons can enter or leave a battery. In your case, the electrical current entered your tongue, which is why you felt a tingle.
So why were we able to stick electrodes into a lemon and get a battery? All voltaic batteries need their metals to be placed in an electrolyte. An electrolyte is a substance that can carry electrical current when dissolved in water. The tiny bit of salt in your saliva makes your saliva an electrolyte, and the sour citric acid does the same thing for lemon juice. Batteries stop working when there is not enough of the electrolyte to react with the metal or not enough metal left to react with the electrolyte.
One Step Further…
You can generate more electrical current by connecting multiple lemon batteries. Just make a second battery and connect the zinc or steel piece of one battery with the copper wire of the other battery using another piece of copper wire to act as a bridge.
You can use your enlarged lemon battery to power a low-power device like an LED bulb or a small digital clock. Remove the regular battery from the digital watch or calculator. Then, hook up the copper electrode of your lemon battery with the battery slot’s positive contact. Connect the zinc or iron electrode with the negative contact. Can you get the device to work?
If you are looking to test a variable, try making batteries using different fruits and vegetables. Which ones produce the biggest tingle on your tongue? Which ones generate the most electric current?
Feeling A Little Lazy?
Go ahead and buy a kit like the one we used! They’re inexpensive and widely available on Amazon.
Have you seen what our friends have created this week?