Application of Electrostatics

Spray painting

As the spray leaves the nozzle, it is being charged by friction. Since the droplets all have same charge, they will repel each other as like charges repel, and thus, they spread out evenly.

Advantages
  • Good adhesion of paint onto the object;
  • Smooth and uniform coating of paint;
  • Cost efficient as it reduces the wastage of paint.

Similar principle is used in Crop Sprayer as well.

Electrostatic Precipitator

This is used to remove flue-ash emitted from coal-fired power stations.

Mechanism:
  • Dust and ash particles pass through the fine wires and become negatively charged. 
  • The negatively charged dust and ash particles are attracted to the positively charged plate since unlike charges attract. 
  • The dust and ash particles are then scraped and removed from the plates.

Laser Printer

Laser Printer electrostatic
Courtesy of Answers.com
  • When rotating, the drum surface becomes positively charged.
  • The laser beam then casts an image of the data to the rotating drum and exposes other parts of drum surface to laser to be discharged. By doing so, it creates a positively charged pattern which is similar to the print pattern.
  • The negatively-charged toner is then attracted to the positively-charged pattern on the drum as unlike charges attract, and is transferred to the paper.
A more detailed process is elaborated in following video.
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