Topics covered in this chapter are:
- Current Density and Ohm's Law
- Electromagnetic force and Kirchoff's Voltage Law, Continuity Equation and Kirchoff's Current Law.
- Power Dissipation and Joule's law
- Boundary Conditions for Current Density
Introduction:
In our discussion so far we have considered field problems that are associated with static charges. In this chapter we consider the situation when the charges can be in motion and thereby constituting current flow.
Due to the movement of free charges, several types of electric current can be caused:
Conduction Current is due to the drift of electrons and/or holes and occurs in conductor and semiconductor. Motion of ions gives rise to electrolytic currents and convection current results from motion of electrons and/or ions in an insulating medium such as liquid, rarified gas and vacuum.
It is worth mentioning here that in time varying scenario, bound charges give rise to another type of current known as Displacement current, which we shall consider in more detail in later chapters. |