Applications
Flue-ash removal: using an electrostatic precipitator, flue-ash (smoke and dust) can be removed from a coal power station. Flue-ash causes serious air pollution. A precipitator consists of wires which are negatively charged and plates which are positively charged. The wires charge ash particles when they pass and the plates attract these charged particles. The plates are then mechanically shaken to remove the ash. This technique is widely used in industries which release flue gases.
High voltage generators: the Van de Graaff generator is used in nuclear research to accelerate sub-atomic particles. It sis a static charge generator with a voltage production of up to 14 million volts.
Spray painting: Electrostatic spray painting is used in the production of cars, where the car and the nozzle (paint) are oppositely charged which causes adhesion of the paint to the car giving a uniform layer of paint.
Laser Printer, Photocopier:
At the heart of a printer is a metal drum coated with an insulating material . The drum rotates and goes through a series of processes to produce an image on a piece of paper.
Hazards
Lightning: thunderclouds are charged due to the friction between water and air molecules. Large quantities of electric charge produces flashes of lightning. When the charge on thunderclouds is sufficient it ionises the air which provides a conducting path for the large amounts of charge to be discharged to the nearest object on the ground. Lightning conductors are placed on tall buildings to prevent damage, by providing a discharge path for the electrons to flow into the earth.
Fires or Explosions: a fire or explosion can be caused by the massive build-up of electric charges produced by friction. Electric charge accumulate on planes and trucks carrying flammable liquids. Therefore preventive steps are taken e.g. an aircraft’s tyres are made of a slightly conductive rubber which discharges the electric charge during touchdown.