Electric charge is a fundamental physical property of matter. Unlike mass, however, the charge carried by a particle can be positive, negative, or zero. Charges are found every where and in great abundance. Actually, a normal atom is composed of an equal number of positively charged protons and negatively charged electrons, in addition to neutral (or uncharged) neutrons. In such state, the atom is a neutral particle carrying zero net charge. However, it can turn into a charged particle (or ion) if it loses or gains an electron.
Two objects carrying similar charges (both positive or both negative), exert repulsive forces on each other. Oppositely charged objects, however, attract each other. This electric force becomes stronger when the quantity of charge on either object increases or if the distance between them decreases. In this experiment, you will investigate the relationship between electric force and distance for two charged objects.