P4b Flashcards
(6 cards)
How can electrostatics be useful for electrostatic precipitators?
They remove the dust or soot in smoke and are used in chimneys.
How is static electricity used in electrostatic dust precipitators to remove smoke particles from chimneys?
As the smoke particles reach the bottom of the chimney, they meet a wire grid with a high voltage and negative charge. The dust particles gain electrons and become negatively charged. The dust particles then induce a charge on the earthed metal plates (the negatively charged dust particles repel electrons on the plates, so that the plates become positively charged). The dust particles are attracted to the metal plates, where they stick together to form larger particles. When heavy enough, the particles fall off the plates or are knocked off by a hammer. The dust falls to the bottom of the chimney and can be removed.
How can electrostatics be useful for spraying?
For spray painting and crop spraying.
How is static electricity used in paint spraying?
The spray gun is charged, which charges up the small drops of paint. Each paint drop repels all the others, since they’ve all got the same charge, so you get a very fine spray. The object to be painted is given an opposite charge to the gun. This attracts the fine spray of paint. This method gives an even coat and hardly any paint is wasted. Parts of the bicycle or car pointing away from the spray gun still receive paint too - there are no paint shadows.
The paint could be negatively charged so it’s gained electrons and the bike or car could be positively charged so it’s lost electrons.
How can electrostatics be useful for defibrillators?
They are useful for restarting the heart when it has stopped. Defibrillators work by discharging charge. They give an electric shock to the heart so it can start beating again.
How can static electricity be useful for restarting the heart when it has stopped?
The defibrillator consists of two paddles connected to a power supply. The paddles of the defibrillator are placed firmly on the patient’s chest to get a good electrical contact and then the defibrillator is charged up. Everyone moves away from the patient except for the operator who holds insulated handles - so only the patient gets the shock. The charge passes through the paddles to the patient to make the heart contract.
