Some natural phenomenon of Class 8
About Electric Charge
From the study of atomic structure, we know that an atom consists of a central part called nucleus and around the nucleus (called extra-nucleus) there are a number of electrons revolving in different paths or orbits. The nucleus consist of protons and neutrons. A proton is a positively charged particle while a neutron has no charge. Therefore, the nucleus of an atom bears a positive charge. An electron is a negatively charged particle having magnitude of negative charge equal to the magnitude of positive charge on a proton. Normally, the number of electrons is equal to the number of protons in an atom. Therefore, an atom is neutral as a whole, the negative charge on electrons cancelling the positive charge on protons. This leads to the conclusion that under ordinary conditions, a body is neutral, i.e. it exhibits no charge. When a body has deficiency or excess of electrons from the normal, it is said to be charged or electrified.
TYPES OF CHARGE:
There are two types of charges known as positive and negative charges. All objects normally contain equal amount of positive and negative charges and are therefore, electrically neutral.
Eg. (i) When we comb dry hair, the comb gets charged and can pick small pieces of paper brought near it.
(ii) When we rub a glass rod with silk cloth or a piece of ebonite rod with woolen material. The charge acquired by a glass rod rubbed with silk is called a positive charge and that on ebonite rod is called a negative charge.
Glass rod and ebonite rod will attract each other while two glass rods as well as two ebonite rods will repel each other.
Like charges repel each other and unlike charges attract each other.