what is Magnetic Field ?

                Magnetic Field

Whenever a current flows through

a conductor, a magnetic field is

established around that conductor.

  the cross-sectional

views of two conductors carrying

current in opposite directions. The

cross sign (¥) shown inside the

conductor indicates that current is

entering the conductor whereas the

dot sign (◊) shown indicates that the

current is coming out in a direction

perpendicular to the plane of the paper. Directions of flux lines around the conductors

are also shown in the figure. The direction of the lines of force around a conductor

is readily determined by the right-hand rule which is as follows—point the thumb

of the right hand in the direction of the current in the conductor and wrap the fingers

of the right hand around the conductor. The finger tips will point in the direction of

the lines of force.

The cork screw rule can also be applied to determine the direction of the lines of

force around a current-carrying conductor.

Concentration of flux can be produced by causing the current to flow through

a coil instead of through a conductor. Inside the coil the flux contributed by each

segment of the coil is in the same direction. Thus a strong magnetic field is produced

due to current fl owing through a coil. The introduction of a

magnetic material as a core for the coil increases the flux. A simple right-hand rule

indicates the direction of magnetic flux inside a coil: Wrap the fingers of the right

hand around the coil, with the finger tips pointing in the direction of the current, the

thumb points in the direction of the magnetic flux.