Introduction

Introduction

• Uptill now static electrostatic fields are discussed. The electrostatic field exists due to the static charges i.e. charges at rest. The magnetic field exists due to a permanent magnet, which is a natural magnet. But in electromagnetic engineering a link between electric and magnetic field is required to be studied. Such a link is absent with magnetic field due to a natural magnet.

• The scientist Oersted has discovered the relation between electric and magnetic fields in 1820. Scientist Oersted stated that when the charges are in motion, they are surrounded by a magnetic field. The charges in motion i.e. flow of charges constitutes an electric current. Thus a current carrying conductor is always surrounded by a magnetic field. If such a current flow is steady i.e. time invariant then the magnetic field produced is a steady magnetic field which is also a time invariant. The direct current (d.c.) is a steady flow of current hence magnetic field produced by a conductor carrying a d.c. current is a static steady magnetic field. The study of steady magnetic field, existing in a given space, produced due to the flow of direct current through a conductor is called magnetostatics. The various other concepts like e.m.f. induced, force experienced by a conductor, motoring action, transformer action etc are dependent on the magnetostatics. Hence the study of steady magnetic field i.e. magnetostatics plays an important role in the engineering electromagnetics. This chapter explains the steady magnetic field in free space due to the conductor carrying a direct current.