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Science

Uses of electrostatics

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Electrostatic precipitators

Many power stations burn fossil fuels such as coal and oil. Smoke is produced when these fuels burn. Smoke comprises tiny solid particles, such as unreacted carbon, which can damage buildings and cause breathing difficulties. To avoid this, the smoke is removed from waste gases before they pass out of the chimneys. The electrostatic precipitator is the device used in chimneys for this job.

Smoke particles pick up a charge as they pass the charged metal grid. These smoke particles are attracted to oppositely charged collecting plates.

Smoke particles pick up a negative charge as they pass the negatively charged metal grid. These smoke particles are attracted to positively charged collecting plates

In the example above:

  1. Smoke particles pick up a negative charge
  2. Smoke particles are attracted to the collecting plates, which are earthed or positively charged
  3. Collecting plates are knocked to remove the smoke particles, which then fall into a collector.

Higher Tier

The metal grids in the electrostatic precipitator are given a high voltage. Depending on the design, the grids may be positively charged or negatively charged

  • dust particles lose electrons if the grids are positively charged
  • dust particles gain electrons if the grids are negatively charged.

The charged dust particles then induce a charge on the earthed metal collecting plates and the dust particles are attracted to the plates.

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