Activity Title: Green STEM Challenge: Light from Lemons
- School Age
Lemons are good for more than just lemonade, they also make good batteries!
What do I need?
For this activity, you will need the following items:
1. Lemon (any lemon will do, but a lemon with a thinner rind will make a better battery)
2. Copper Coins - Pennies
3. Galvanized nails (Galvanized nails have a zinc coating that is important to this experiment)
How do we do it?
1. Rinse the penny with a light detergent to ensure you are working with a clean surface.
2. Squeeze the lemon without breaking its skin. You can roll the lemon on a table applying a small amount of downward pressure. The squeezing action releases the juices inside the lemon needed for the battery to work.
3. Cut a small slit through the rind in the middle of the lemon. The slit needs to be large enough to insert the copper penny about halfway into the lemon.
4. Insert the penny and the nail into the lemon. The penny should fit nicely into the slit you’ve already made.
5. The nail should be pushed into the lemon about 2 centimeters away from the penny. These items will serve as the positive and negative ends of your battery.
6. The metals need to be close to each other in order for the necessary chemical reaction to take place. Be careful not to have the nail and penny touch within each lemon. If they touch, the battery will short circuit and you won’t get any voltage.
7. Make sure the penny and the nail are deep enough to be in contact with the juice of the lemon.
8. Attach the voltmeter clips to the nail and penny. Using the end clips of the voltmeter, attach one clip to the nail and the other clip to the penny. You should see a small increase in voltage on the voltmeter.
What is the science behind it?
We use batteries for almost everything - they are used to power up most device from toothbrushes, to remote controls to computers and tablets. A battery generates electricity by passing electrons between two different metals (one positively charged and one negatively charged). The electrons create a current as they pass through a solution containing molecules that carry the charged particles back and forth between the two different metals.