What is Static Electricity?
Rubbing a polythene strip on wool causes some of the outer electrons in the wool to move over to the polythene strip. As the polythene gains electrons it becomes negatively charged. The wool looses electrons and is left with a net positive charge (more protons to electrons).
Static electricity is caused by the transfer of charge.
Atoms are made up of protons, neutrons and electrons each with their own properties.
Protons have a Positive (+) charge.
Electrons have a Negative (-) charge.
Neutrons are Neutral (no charge).
The positive charges (protons) are held in the nucleus of the atom.
The negative charges (electrons) are spread in orbits around the nucleus.
The protons and neutrons are held very tightly in the nucleus. But some of the electrons are held very loosely and can move from one atom to another. If an atom looses an electron the number of protons (positive charges) exceeds the number of electrons (negative charges) and the atom is positively charged.
If an atom gains an electron the number of protons (positive charges) is lesser than the number of electrons (negative charges) and the atom is negatively charged.
One method in which electrons can be moved or transferred is by rubbing two insulators together. Rubbing causes friction between the two surfaces increasing the surface contact and allowing more electrons to be transferred. The object which looses electrons becomes positively charged and the one that gains the electrons becomes negatively charged.