1. Type of charges
1.1. positive charge e.g. glass rubbed with silk perspex rubbed with wool
1.2. negative charge e.g. amber rubbed with fur rubber rubbed with fur polythene rubbed with wool
2. methods of charging
2.1. by rubbing
2.1.1. as fur rubs the amber, electrons from the fur deposits on the amber. This makes the amber negatively charged while the fur is positively charged
2.2. by induction
2.2.1. defined as the production of electric charges on the surface of a conductor when under the influence of an electric field
2.2.1.1. can be repeated my times without loss of charge
2.3. by induction earthing process
2.3.1. similar as normal induction just with earth used rather than two conductors
3. law of charges
3.1. like charges repel. unlike charges attract.
4. Dangers and application of electrostatics
4.1. dangers
4.1.1. friction on the tires of a lorry moving makes its metal body become positively charged by induction. this can cause sparks which can ignite a flammable load
4.1.1.1. a chain or conducting strip is dangled from the lorry to earth its metal body
4.1.2. synthetic fibers in clothes can easily be charged by rubbing. charges can be picked up by walking on carpets made of synthetic material. a spark on a dry day, can ignite the clothes
4.2. application
4.2.1. printing
4.2.1.1. static causes toner to stick to a selenium coated drum which will then print
4.2.2. precipatators
4.2.2.1. removes ash and dust with electrostatic by ionizing the air thus charging the ash and dust which will then get stuck to the metal plates
4.2.3. paint spraying
4.2.3.1. using electrostatic can ensure the paint is equally coated
5. Electric fields
5.1. rules in sketching electric fields
5.1.1. no two field lines can cross each other
5.1.2. lines must go from positive to negative charges
5.1.3. number of lines leaving a positive charge is proportional to the magnitude of the charge