Oersted’ s Experiment
A magnetic field is produced in the surrounding of any current carrying conductor. The direction of this magnetic field can be obtained by Ampere’ s swimming rule.
SI unit of magnetic field is Wm-2 or T( telsa).
The strength of magnetic field is called one tesla, if a charge of one coulomb,
when moving with a velocity of 1 ms-1 along a direction perpendicular to the direction of the magnetic field experiences a force of one newton.
1 tesla( T) = 1 weber metre-2( Wbm-2) = 1 newton ampere-1 metre-1( NA-1 m-1) CGS units of magnetic field are called gauss or oersted. 1 gauss = 10-4 tesla.
Maxwell’ s Cork Screw Rule
If a right handed cork screw is imagined to be rotated in such a direction that tip of the screw points in the direction of the current, then direction of rotation of thumb gives the direction of magnetic line of force.
The conventional sign for a magnetic field coming out of the plane and normal to it is a dot i. e.,
The magnetic field perpendicular to the plane in the downward action is denoted by ®.
Ampere’ s Swimming Rule
If a man is swimming along the wire in the direction of current his face turned towards the needle, so that the current enters through his feet, then north pole of the magnetic needle will be deflected towards his left hand.
Magnetic Field
The space in the surrounding of a magnet or any current carrying conductor in which its magnetic influence can be experienced.