A common middle school or elementary school project is to create a battery using a citrus fruit that is able to conduct electricity and light a light bulb. It is an inexpensive and fun project and it can be an exciting way to get interested in science. Why does this workLemons Can Produce Electricity
Lemons are a unique fruit because the juice of a lemon is extremely acidic in nature.
- Lemon juice is highly concentrated with citic acid, which gives the fruit a bitter taste, but also makes it a great conductor of electricity.
- When acids are dissolved into water, the acids break apart into positive and negatively charged ions. These ions have the power to conduct electricity through a liquid like lemon juice.
- Through a process known as oxidation-reduction, the citric acid in the lemon juice and the metals pushed into the flesh of the lemon will form a reaction which results in an electric current. One metal will lose its electrons, a process known as oxidation, and other metal gains those lost electrons, a process known as reduction.
- Because the citiric acid in the lemons is so highly concentrated, all it takes is a few pieces of metal to yield an electric output much like that of a battery's electric current.
Although a lemon does not have enough power to light a large flashlight, it can conduct electricity and you can run an experiment to light up a small light bulb to see the proof.
This experiment works with other citrus fruits as well. However, lemons work the best because lemons are one of the more acidic citrus fruits. If you don't have a lemon to use for the experiment, try these other citrus fruits:
It is important to note when exploring how lemons produce electricity, that lemons, specifically lemon juice on its own, cannot produce an electric current. Lemon juice has to react with a metal element in order to yield a current of flowing electrons.
Here's why it works:
- The lemon juice, which is very acidic, basically produces a chemical reaction with the paper clip which is made of zinc, and the penny which is made of copper.
- The acids of the lemon juice and the raw elements of the penny and paper clip meet, and they simultaneously produce a reaction - which is an electic current much like a battery makes.
- Essentially, what the Voltmeter is recording is the movement of electrons from the paperclip to the penny, and outward to produce electricity.
To perform an experiment to see lemon juice conduct electricity, you need the following items:
- Paper clip
- A multitester (either digital or analog) or Voltmeter
A multitester or Voltmeter is a tool that is used to check resistance, continuity, and voltage in electrical components.
Preparing the Lemon
You need to ensure that the juices are free to move within the fruit in order to conduct electricity. You can do this be either squeezing the lemon, or rolling the lemon on a flat surface. Be careful as you either squeeze the lemon or roll the lemon because you do not want to break the skin of the fruit.Making the Lemon Conductor
After you are finished rolling the lemon, set it aside. You can either use the lemon whole or cut it in half.
Here's how to make the lemon a conductor:
- Straighten the paper clip out until there are no more bends in the paper clip. Be careful when you do this because you do not want the paper clip to break.
- Take the straightened paper clip and insert it into your lemon. You want to insert the paper clip about an inch deep into your lemon.
- Insert a penny into your lemon about a quarter-inch deep, at least until ther penny has pierced the skin of the fruit.
- There will be two wires that are already attached to the multitester or Voltmeter, one red (+) and one black (-). Each wire will have an alligator clip.
- Using the alligator clips, connect the red wire to the penny, and the black wire to the paper clip. Check for a reading on the multitester or Voltmeter. If your lemon produces a reading, then there is a flow of electricity through the lemon.
Once you have electricity flowing through the lemon, you can attach the wires to the metal base of a small flashlight bulb. If the lemon is generating electricity, the bulb will light up.