# Static Electricity

Electricity is indispensable to us. The source of electricity and electrical phenomena are electric charges. We study phenomena related to charges at rest under static electricity and phenomena related to charges in motion under current electricity.

Greeks were familiar with the fact that amber when rubbed with fur attracts small objects. Dr. Gilbert called these substances as electrics. The bodies which on rubbing acquire the property of attracting light objects are said to be electrified or charged. The charged bodies possess electric charges by virtue of which they interact with each other. The force of interaction is called electric force.

# Two Types of Charges

Electric charges occur in two varieties namely, positive and negative. By convention, a glass rod rubbed with silk is said to acquire positive charges. An ebonite rod rubbed with fur is said to acquire negative charges, similar to magnetic poles like charges repel and unlike charges attract.

From modern view, the atoms of which the matter is made up of consist of an equal amount of positive and negative charges. The negative charges are carried by electrons and positive charges in the nucleus by protons.

By certain processes electrons from the atoms of one body can be transferred to another body. Then the body which gains electrons get negatively charged and the body which loses electrons gets positively charged.

# Electrification of a Body

A body can be charged or electrified in many ways; two of the methods are given below.
1. Charging by friction

When two bodies are rubbed against each other, one of them loses electrons and hence gets positively charged. The body that gains electrons gets negatively charged.
2. Charging by conduction

When a charged body is brought in contact with an uncharged body, it shares its charges with it. Thus, the uncharged body becomes charged.