Static Electricity – Charging by Rubbing, Attraction, Repulsion and the Electroscope
Integrated ScienceElectricity & MagnetismAges 13–14
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Sign in to playRub a balloon, a glass rod or a plastic ruler with wool, silk or hair: electrons move from one object to the other according to the triboelectric series, so the two objects gain opposite charges. Hang the objects to see like charges repel, unlike charges attract and neutral objects are attracted by induction; bring a charged object near scraps of paper; use a gold-leaf electroscope to detect charge, charge by contact and by induction, and earth it.
Lesson: Charging by friction; positive and negative charges; forces between charged objects
What it shows
When two different materials are rubbed together, electrons move from the material that holds them less tightly to the other one, so both become charged: one positive, one negative, with equal amounts. This simulation uses a simplified triboelectric series of six materials. Charged objects hanging on threads show that like charges repel and unlike charges attract, while neutral objects such as paper scraps or a light aluminium ball are attracted because their charges shift (induction). A gold-leaf electroscope shows detection of charge, charging by contact and by induction, and earthing.
How to use
Choose Object A and Object B, then drag A back and forth over B or press Rub; watch electrons jump and the charge tags change. Switch Experiment to Hanging objects attract or repel and pick the Second hanging object; drag the ↔ stand to change the distance. In Picking up paper scraps, drag A towards the table. In Gold-leaf electroscope, bring A near the cap, touch it, and use Earth the electroscope. Earth object A makes a spark.
Parameters you can change
- Experiment Rubbing two objects, Hanging objects attract or repel, Picking up paper scraps, Gold-leaf electroscope
- Object A Balloon (rubber), Glass rod, Plastic ruler (polythene)
- Object B (rubbed with A) Piece of wool, Piece of silk, Hair
- Show charges
Questions to explore
- When glass is rubbed with silk, why does the glass become positive and the silk negative?
- Why is a neutral paper scrap or aluminium ball still attracted to a charged object?
- How can you give the electroscope a charge opposite to the plastic ruler without letting them touch?
