The static electricity is the result of an imbalance between the positive and negative charges of an object.
To understand the phenomena of static electricity, first we need to understand the basics of atoms and charges.
All the physical objects are made up of atoms. The atoms in turn made up of electrons, protons and neutrons. The electrons are negatively charges, protons are positively charged and the neutrons does not possess any charge. Therefore, all the physical objects are made up of charges.
The opposite charges (positive and negative) attract each other while the like charges (positive and positive or negative and negative) repel each other. Most of the time, the positive and negative charge in an object remains equal, which makes the object electrically neutral.
The static electricity is the result of imbalance between the positive and negative charges of an object. When the electrons are extracted out from an object, the object becomes positively charged while when electrons are transferred to the object, the object becomes negatively charged. As the displaced electrons try to remain stationary after being moved from one object to the other, for this reason it is called “static electricity”.
The rubbing of certain materials with each other, there be a transfer of electrons takes place between the objects. For instance, when a balloon have rubbed against the hairs, some electrons are transferred to the surface of the balloon, hence the wall is now more positively charged than the balloon. When the two come in contact, the balloon will stick to the wall since the opposite charges attract each other.
Also, after rubbing a glass rod against a piece of silk cloth, the silk and glass would attract each other. This is because when the glass rod and silk having been rubbed, there is a transfer of some electrons from glass rod to the silk takes place which makes the two oppositely charge with respect to each other. Hence, the glass rod and silk attract each other, according to the rule, opposite charges attract.
This phenomenon became more interesting when it was discovered that when the two objects made of identical material are rubbed with their respective cloths, they always repel each other. For example, when two glass rods are rubbed to silk cloth, and brought near to each other. The two glass rods repel each other since both the have same charges on the surface.
One most common use of static electricity is in photocopiers and printers where static electric charges attract the ink to the paper.
Used in the electrostatic air filters.
Used in the high voltage Van de Graaff Generator.