Make Lightning at Home
Lightning is a discharge of static electricity. Tiny charged particles called electrons build up until the cloud can’t hold any more — then they move! This build up of charged particles is caused by strong updrafts that carry moist, icy air upward into a thunderstorm where heavier liquid droplets are falling. The ice and liquid collide and transfer electrons from the ice to the liquid water. The ice becomes positively charged as it moves to the upper part of the cloud while the liquid becomes negatively charged as it moves to the lower part.
When the cloud gets so much electric charge that it cannot hold any more, the electricity moves in a giant spark, sometimes from the bottom of the cloud to the top, and sometimes from the cloud to the ground! These giant sparks are what we call lightning.
When lightning forms it superheats the air. This makes the air expand rapidly. That quick moving air makes a very loud sound that we call thunder.
Let’s make our own slightly smaller bolt of lightning with things you likely have in your own home! The device we’re building is sometimes called an electrophorus.
Here’s what you’ll need:
- Styrofoam plate or to-go container
- Aluminum pie tin
- Pencil with an eraser
- Wool sweater, wool sock or even your own hair
Here’s what to do:
Step 1: Use your thumbtack to put a hole through the center of your pie tin. Push the eraser side of your pencil into the tack, creating a handle. This creates a handle of insulating Styrofoam on the aluminum. Aluminum is a conductor, the opposite of an insulator. Conductors like aluminum let electrons move very easily.
Step 2: Take the Styrofoam plate and build up some charge in it by rubbing it with a wool sweater or a wool sock. If you absolutely have to, you can use your own hair if it’s long enough. This moves electrons to the Styrofoam and gives it a negative charge. Styrofoam is an insulator. That means it holds tightly to electrons and doesn’t let them move very easily.
That’s it! Two steps, and your electrophorus is ready to go.
Now let's make some lightning:
1. Carefully set the aluminum pie pan on top of the Styrofoam plate, thumbtack side down. The negative charges in the Styrofoam plate pull positive charges toward it and push negative charges away inside the aluminum. The side of the plate touching the pan becomes positive and the side that is not touching becomes negative.
2. Use your finger (or the fork, if you don’t want to feel the shock) to slowly touch the edge of the pie pan. When you do this, you take the negative charges away from that side of the pie pan and create a spark!
3. Use the pencil as a handle to pick up the pie tin. Now the positive charges are no longer attracted to the Styrofoam, so they spread out throughout the aluminum and if you touch the pan anywhere, you’ll get another shock.
This process can be repeated over and over by lifting and gently dropping the pan on to the Styrofoam plate. Eventually the electrons will leave the Styrofoam and it will not work as well as it did when you first charged it. If you want to charge it again, rub it again with your wool!
This electrophorus is fun, but it can be more fun through some experimentation. Here are some ideas to get you started.
- What works better: a wool sock, a sweater, your hair?
- What else can you try?
- What would happen if you used a stack of Styrofoam plates instead of just one?
- Does it work better on rainy days or dry days?
- Who in your home likes to get shocked by the spark of lightning? Who doesn’t like it even one bit?