Static electricity

Static electricity

1. The build up of static is caused by friction.

   • When certain insulating materials are rubbed together, negatively charged electrons are scraped off one and dumped on the other.
   • This will leave a positive static charge one one and a negative static charge on the other one.
   • Which way the electrons are transferred depends on the two materials involved.
   • Electrically charged objects attract small objects placed near them.
   • A classic example is with polythene and acetate rods being rubbed with a cloth duster.
     • With the polythene rod electrons move from the duster to the rod.
     • With the acetate rod electrons move from the rod to the duster.

2. Only electrons move, never positive charges.

   • Both +'ve and -'ve electrostatic charges are produced by the movement of electrons.
   • A positive static charge is caused by electrons moving away, that material that loses electrons becomes positive.

3. Like charges repel, opposite charges attract

   • When two electrically charged objects are brought close together they exert a force on each other.
   • The forces get weaker the further apart the two things are.

4. Charges can move easily through conductors.

   • Electrical charges can move easily through some materials, these materials called conductors. For example metals are good conductors.