What a learner can do afterwards
- Explains that rubbing transfers electrons from one material to another, creating opposite charges
- States that like charges repel and unlike charges attract
- Links the concept of static discharge to the formation of lightning as a large-scale electric spark
The lesson
Every object is made of atoms, and atoms have tiny parts called electrons that carry a negative charge. When you rub two objects together, like a balloon and your hair, some electrons jump from one object to the other. The object that loses electrons becomes positively charged, and the object that gains electrons becomes negatively charged. That buildup of charge is called static electricity.
Rub a balloon on your hair, then slowly pull it away. Your hair strands often stand up and spread apart. Each strand loses electrons to the balloon, so all the strands end up with the same positive charge. Since like charges repel, the strands push away from each other and reach toward the balloon.
Charged objects follow one rule: like charges repel, and unlike charges attract. Two negative charges push apart, two positive charges push apart, but a positive charge and a negative charge pull together. That is why a negatively charged balloon can stick to a wall. It pulls the wall's charges just enough to hold itself in place.
Lightning works the same way on a much bigger scale. Inside a storm cloud, ice crystals and water droplets rub against each other and build up a huge charge. When that charge grows large enough, it jumps between the cloud and the ground as one giant spark, which is lightning.
Rubbing moves electrons and builds up charge, unlike charges attract while like charges repel, and lightning is that same kind of spark on a giant scale.
Watch it
Where it sits
This opens up
Nothing builds on it yet.
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.