Static Electricity Chapter 12 Pages 134 140 Static

Static Electricity Chapter 12 Pages: 134 -140

Static Electricity occurs in nature

In ancient times it was noticed that if a substance called amber was rubbed it attracted light objects like dust and leaves to it.

Objects like a plastic biro, a polythene rod, or a perpex rod etc. . become charged when rubbed with a wollen cloth or other materials. They can then attract small pieces of paper.

Static electricity involve charges that remain at rest on an object.

When two objects are rubbed together electrons are transferred from one to the other. Friction causes static electricity

An object becomes positively charged if it looses electrons and negitively charged if it gains electrons.

Like Charges repel each other Unlike charges attract.

Insulators Substances like plastic and rubber are electrical insulators. This means that they don’t allow charges to flow through them easily.

A conductor is a substance that allows charge to flow through it freely eg. metals.

Earthing means connecting an object to the earth by means of a conductor so that the object shares its charge with the earth. While an object is earthed a charge cannot build up in it.

To demonstrate the force between charged objects Charge a plastic rod by rubbing it with a cloth and then hang it from a retort stand. Rub another rod with the same cloth (so that it will have the same charge) and bring it up to the first rod.

Useful effects of static electricity Removing soot from chimneys Spray-painting

Nuisance effects of static electricity Television screens attracting dust Lightning