Spark image

Electrostatics in everyday life

When you take off a pullover over a nylon shirt there is a crackling sound
A pen rubbed with a piece of cloth will pick up small pieces of paper
A television screen easily collects dust
You sometimes get a small electric shock when getting out of a car
If you roll over in bed you can sometimes see small flashes of light between the sheets
You can sometimes get a small electric shock from a cat that has rolled on a synthetic carpet
In a thunder storm there are huge flashes of lightning
Book covering film can be difficult to work with

Other detailed applications

1. A charged mesh in a chimney acts as an electrostatic dust collector, cleaning the smoke.
2. Paint sprays can be charged and the object they are spraying earthed to attract the paint towards it.
3. Vinyl records have to be cleaned to remove the static charge that builds upon their surface.
4. People thought that static electricity was the cause of car sickness until it was remembered that a static charge can only be on the outside of a hollow conductor like a car.
5. Photocopiers work by a charged sheet attracting fine carbon powder to make the image
6. It can be shown that a water molecule is polar - that is it has one positive end and one negative one. A stream of water can be deflected by a charged polythene rod placed nearby
7. Capacitors
A capacitor stores static charge - in its simplest form it is two plates that are separated by air. More charge can be stored by increasing the area of the plates, putting them closer together or using another insulator instead of air. In a practical capacitor the plates are usually rolled up with paper insulation in between them. In a radio receiver a variable capacitor with moveable plates is used as the tuner.
8. People must take care when emptying oil tankers and refuelling aircraft to avoid a build up of static charge due to friction that could make a spark and result in an explosion.
9. Problems and uses of cling film
10. Sellotape sticking to everything except what you want it to when you pull it off the roll

© Keith Gibbs 2020