Uses of Electrostatics

Question 1

How do dust precipitators work?

Answer 1

• Prevent harmful particles from factories from escaping and polluting the atmosphere
• Metal grid in the chimney is given a large charge from a high-voltage supply
• Plates inside the chimney are earthed and have an opposite charge to the grid
• As dust particles pass the grid they become charged with the same charge as the grid as they gain or lose an electron
• They are attracted to the plates because they are oppositely charged
• The plates vibrate at intervals so the dust falls into a collector

Question 2

How is static used in spray painting?

Answer 2

• The spray gun is charged and all the paint particles gain the same charge
• The object should be oppositely charged otherwise the object would gain the same charge as the paint and the paint droplets would repel at the edges
• As the paint is sprayed, the droplets are attracted to the object so less paint is wasted
• The object gets an even coat because the paint droplets will repel each other because they have the same charge

Question 3

How do defibrillators work?

Answer 3

• Delivers electric shock to the heart through the chest wall to restore rhythm
• Two paddles charged from high-voltage supply
• Placed onto chest to ensure good electrical contact
• Electric charged passed through patient to make their heart contract
• Power = energy/time