ELECTROSTATICS In this unit, student is exposed to • Historical background of electricity and magnetism • The role of electrostatic force in day – to-day life • Coulomb’s law and superposition principle • The concept of electric field • Calculation of electric field for various charge configurations • Electrostatic potential and electrostatic potential energy • Electric dipole and dipole moment • Electric field and electrostatic potential for a dipole • Electric flux • Gauss law and its various applications • Electrostatic properties of conductors and dielectrics • Polarisation • Capacitors in series and parallel combinations • Effect of a dielectric in a capacitor • Distribution of charges in conductors, corona discharge • Working of a Van de Graaff generator Electricity is really just organized lightning – George Carlin Learning Objectives . INTRODUCTION Electromagnetism is one of the most important branches of physics. The technological developments of the modern st century are primarily due to our understanding of electromagnetism. The forces we experience in everyday life are electromagnetic in nature except gravity.
In standard XI, we studied about the gravitational force, tension, friction, normal force etc. Newton treated them to be independent of each other with each force being a separate natural force. But what is the origin of all these forces? It is now understood that except gravity, all forces which we experience in every day life (tension in the string, normal force from the surface, friction etc.) arise from electromagnetic forces within the atoms.
Some examples are 12th - 12th - - - - - Unit Electrostatics after rubbing with animal fur attracted small pieces of leaves and dust. The amber possessing this property is said to be ‘charged’. It was initially thought that amber has this special property. Later people found that not only amber but even a glass rod rubbed with silk cloth, attracts pieces of papers.
So glass rod also becomes ‘charged’ when rubbed with a suitable material. Consider a charged rubber rod hanging from a thread as shown in Figure . . Suppose another charged rubber rod is