The study of electric charges at rest is called electrostatics. Its other name is ‘static electricity’. A Greek philosopher ‘Thales’ in 600 BC conducted an experiment. He observed that when amber was rubbed with some woolen cloth it gets charged and immediately started attracting small pieces of paper, corks, dust particles, etc. Amber is a yellowish brown translucent substance found along some of the famous seacoasts and is also used in jewelry items. Greek name of ‘Amber’ is ‘Electrum’. It was originated from the words electric charge, electric field, electric force, electricity and electron.
Then William Gilbert published a book named ‘De magneto’ in 1600 A.D. In this book he assigned the name ‘Electrica’ to the substances like amber, which after rubbing with certain materials starts attracting the small bodies. After conducting all his experiments on Frictional electricity, he said that the type of charge generated on a piece of Amber is called ‘Resinous’. Amber is a resin that’s why its charge was named so.
As the time passes Benjamin Franklin introduced his new theory. According to which, charge present on the piece of amber was ‘negative’ and the charge present on wool was ‘positive’. His theory was absolutely correct. Scientists are still following it.
Electrostatics is also called as ‘frictional electricity’. When two non insulating bodies are rubbed with each other then the charges at rest are generated due to the presence of friction in them.
So, when a glass rod is rubbed with a piece of silk cloth then it gets charged. In other words we can say that rod is ‘Charged’ or ‘Electrified’.
Some examples: Similar is the case of Comb. It also gets charged or electrified when it is passed through dry hair. A paper sheet also gets charged when it is passed through the machine in the printing press.
What are the applications of electrostatics:
1. Generators are designed using the property of electrostatics. Its popular example is Van de Graff generator.
2. Spraying of paints, powder, etc using electrostatic spraying technique.
3. In loudspeakers and microphones.
4.Pollution prevention techniques of atmosphere for separation of fly ash.
5. Also used for ink jet printing.