Electrostatics

Electrostatics is a very important step in the study of engineering electromagnetics. Electrostatics is a science related to the electric charges which are static i.e. are at rest. An electric charge has its effect in a region or a space around it. This region is called an electric field of that charge. Such an electric field produced due to stationary electric charge does not vary with time. It is time invariant and called static electric field. The study of such time invariant electric fields in a space or vacuum, produced by various types of static charge distributions is called electrostatics. A very common example of such a field is a field used in cathode ray tube for focusing and deflecting a beam. Electrostatics plays a very important role in our day to day life. Most of the computer peripheral devices like keyboards, touch pads, liquid crystal displays etc. work on the principle of electrostatics. A variety of machines such as X-ray machine and medical instruments used for electrocardiograms, scanning etc. use the principle of electrostatics. Many industrial processes like spray painting, electro-deposition etc. also use the principle of electrostatics. Electrostatics is also used in the agricultural activities like sorting seeds, spraying to plants etc. Many components such as resistors, capacitors etc. and the devices such as bipolar transistors, field effect transistors function based on electrostatics. Hence this chapter introduces the basic concepts of electrostatics.

The study of Electrostatics starts with the study of the results of the experiments performed by an engineer from the French Army Engineers, Colonel Charles Coulomb. The experiments are related to the force exerted between the two point charges, which are placed near each other. The force exerted is due to the electric fields produced by the point charges. A point charge means that electric charge which is spreaded on a surface or space whose geometrical dimensions are very small compared to the other dimensions, in which the effect of its electric field is to be studied. Thus a point charge has a location but not the dimensions. A charge can be a positive or negative.

Questionnaire:

• What is Electrostatics?