الیکٹروسٹیٹکس

Study Notes

Static charges are charges that cannot flow.
All materials are made of tiny particles called atoms.
Atoms contain electrons, protons, and neutrons.
Electrons orbit the nucleus.
Protons and neutrons are called nucleons.
Neutrons have no charge.
Electrons have a negative charge.
Protons have a positive charge.
Atoms are neutral because the number of protons equals the number of electrons.
Electric charges are measured in coulombs (C).
Charging by friction occurs when two materials are rubbed together.
Friction causes electrons to transfer from one material to another.
This creates a static charge on the materials.
Like materials gain the same (opposite) charge.
Example: Rubbing a comb with cloth makes the comb charged.
Materials become charged when electrons are transferred during friction.
Perspex rod rubbed against cloth becomes positively charged.
Polythene rod rubbed against cloth becomes negatively charged.
Unlike charges attract and like charges repel.
Charging by induction: A charged object can induce a charge in a neutral object.
Bringing a positively charged rod near a neutral metal sphere induces a negative charge on the side closest to the rod and a positive charge on the opposite side.
Earthing is connecting a conductor to the Earth to remove unwanted charges.
Lightning is a large electrical discharge between clouds and the Earth.
Lightning conductors prevent buildings from being damaged by lightning.

Electrostatic precipitators remove dust and ash from smoke.
By using oppositely charged plates, the charged dust and ash particles are attracted to the plates.
Electrostatic spraying: Using charged paint droplets to coat objects evenly without wastage
Photocopy machines use static electricity to copy documents.
- A light-sensitive plate gains or loses a charge based on the image.
- Powdered ink is attracted to the charged areas and transferred to the paper.