Static Electricity

 When two bodies are rubbed together, they acquire the property of attracting light objects like small bits of paper, dust particles etc. the bodies which acquire this property are said to be electrified or charged with electricity.

Charge: Charge is the basic property associated with matter due to which it produces and experiences electrical and magnetic effects.

Benjamin Frnkline named the two types of charges as positive and negative.

Similar Charges repel each other and opposite charges attract each other.

Charging of bodies takes place due to transfer of electrons from one body to other body.

A list of materials has been given below. The list is such that any of the material in the list will be positively charged when rubbed with any other material coming later in the list. The other material will naturally be negatively charged.

1.	Fur	2.	Flannel	3.	Shellac	4.	Sealing Wax
5.	Glass	6.	Paper	7.	Silk	8.	Human body
9.	wood	10.	Metals	11.	India Rubber	12.	Resin
13.	Amber	14.	Sulphur	15.	Ebonite	16.	Gutta Percha

Surface density of charge: Surface density of charge is defined as the mount of charge per unit area on the surface of conductor.

The surface density of charge at a point on the surface of conductor depends upon the shape conductor and presence of other conductors or insulators near the given conductor.

The surface density of charge at any part of the conductor is inversely proportional to the radius of curvature of the surface of that part.

This is why surface density of charge in maximum at the pointed parts of the conductor.