Electric charges and fields 01

In this blog you will understand what is frictional electricity, electric charge, electrostatic, application of electrostatic and Electronic theory of frictional electricity. 

Frictional electricity

If a glass rod is rubbed with a silk cloth it is able to attract small pieces of paper, light feathers, etc. 

Similarly, a plastic comb passed through dry hair can attracts such light objects. 

In all these examples we can say that the rubbed substance has become electrified or electrically charged (the property of rubbed substances due to which they can attract light objects is called electricity) . 

Electric charge

It is the inherent propertie pf elementary particles of the matter which gives rise of electric forces due to other charge particles. 

For ex - charge on electron is given by -e and charge on proton is given by +e where the value of "e" Is given by e = 1.6 × 10(of power of -19) coloumb. 

• The SI unit of electric charge is coloumb (C). 

• Generally in the massive bodies the no. Of electrons = no. Of protons, therefore the body remains electrically neutral. 

Electrostatic

It is the branch of physics in which we deals with the study of charges at rest. 

Application of electrostatic

(1). In electrostatic spraying of paints. 

(2). In a Xerox copying machine. 

Experimental study 

(1). To rub a glass rod with a silk cloth and suspended it from a rigid support. Bring another similar charged rod near it, the 2 rods repels each other. 

(2). Bring a plastic rod rubbed with woollen cloth near the charged glass rod, the rod attracts each other. 

From the above experiment, we know that the charge produced on a glass rod is different from the charge produce on a plastic rod. 

We can conclude that

(1). There are only two kinds of electric charges positive and negative. 

(2). The charge developed on a glass rod when rubbed with silk is called positive charge. 

(3). The charge developed on a plastic rod when rubbed with wool is called negative charge. 

(4). Like charges repel each other and unlike charges attract each other (it is known as fundamental law of electrostatics) . 

Two kinds of charges developed on rubbing

Electronic theory of frictional electricity

All matter is made of atoms an atom consist of a small central nucleus containing proton and neutron, around which revolve a no. Of electrons. 

                               Note

(1). Before rub, the substance have equal no. Of protons and electrons and remains electrically neutral. 

(2). The electron in innermost orbit is tightly bond with nucleus and electron in outermost orbit is loosely bond with nucleus and the electron in outermost orbit is called loosely bond electron. 

(3). The minimum energy required to remove free electron from outermost orbit is known as it's work - function energy. 

(4). When two object rubbed together than the electrons starts to transition from the substance have low work function energy

For ex - glass to the substance have high work function energy i.e. silk. 

(5). The substance low work function energy having deficiency of electron and acquires positive charge and the substance having high work function energy have excess no. Of electrons and acquires negative charge.