An electrostatic copier works by arranging positive charges in a pattern to be copied on the surface of a non-conducting drum, and then gently sprinkling negatively charged dry toner particles onto the drum. The toner particles temporarily stick to the pattern on the drum and are later transferred to the paper and ‘melted’ to produce the copy.
In spray painting, particles of paint are give positive charge as they leave the nozzle of a spray gun. The object to be painted is earthed so that there is an electric field between the nozzle and the object. The charged paint droplets follow the field lines are are deposited evenly over the surface of the object.
Tiny particles of soot, ash, and dust are major components of the airborne emissions from fossil fuel-burning power plants and from many industrial processing plants. Electrostatic precipitators can remove nearly all of these particles from the emissions.
The flue gas containing the particles is passed between the series of positively charged metal plates and negatively charged wires. The strong electric field around the wires creates negative ions in the particles. The negatively charged particles are attracted by positively charged plates and collect on them. Periodically, the plates are shaken so that the collected soot, ash, and dust slide down into a collection hopper.