static electricity

static electricity

1. static electricity is caused when two insulators rub together causing friction

   • electrons will be scraped off of one and on to the other leaving one of them with a positive charge (as loss of electrons always makes a positive charge) and a negative on the other. Electrically charged objects attract small neutral objects
     • like charges repel, opposite charges attract

2. static electricity can be a nuisance

   • attracting dust - dust particles are charged and will be attracted to anything with the opposite charge. Unfortunately many objects around the house are insulators that get easily charged and attract the dust particles
   • clothing - when synthetic clothes are dragged over each other or over your head electrons get scraped off leaving static charges on both parts and that lead to attraction and little sparks or shocks as the charges rearrange themselves
   • shocks from door handles - if you walk on a nylon carpet wearing shoes with insulating soles, charge builds up on your body. Then if you touch a metal door handleothe charge flows via the conductor and you get a little shock

3. static electricity can be dangerous if it's near any inflammable gases.

   • dangerous sparks can be prevented by earthing the object to the ground using a conductor

4. uses of static electricty

   • electrostatic paint sprayers - the spray gun is charged which charges up the small drops of paint. Each paint drop repels all the others because they all have the same charge so it is a very fine spray. The object to be painted is given an opposite charge. This method gives you an even coat with hardly any wastage.
   • dust precipitators - a wire grid or rods is put in the chimeny of factories with a negative charge and hig voltage and. Smoke particles meet meet them and gain electrons, becoming positively charged. They then induce a charge on the earthed metal plates and are attracted to the metal plates and form larger, heavier particles when they stick together, They then fall of when knocked off by a hammer which falls to the bottom of the chimney and can be removed
   • defibrillators - an electric shock to a stopped heart can make it start again as your heart is controlled by tiny little electrical pulses inside your body.Defibrillators are used in hospitals to do this. It consists of two paddles connected to a power supply. They are paced firmly on the patients chest to get a good electrical contacts and then is charged up. Everyone moves away apart from the operator (holding insulated handles) so that only the patient gets the shock. The charge then passes through the paddles to the patient to make the heart contract.