Magnetic Field Patterns Produced by Current carrying conductor having Different shapes :
1. Magnetic Field Patterns due to Straight current - carrying conductor :
The magnetic field lines around a state conductor carrying current are concentric circles who centres lie on the wire.
When current is passed through wire ab it produce a magnetic field around it this magnetic field has a magnetic field lines around the wire ab the iron filling get magnetize and on taping the cardboard sheet the iron filling arrange themselves in circles around the wire showing that the magnetic field lines are circular in nature
When current in the wire flow in the upward direction then the lines of magnetic fields are in the anticlockwise direction if the direction of the current in the wire is rivers the direction of magnetic field lines also get reversed.
(i) Magnitude of magnetic field produced by a straight current - carrying conductor :
B = u I/ 2πr
The magnitude of the magnetic field produced by a state current carrying wire is directly proportional to the current passing in the wire and inversely proportional to the distance from the conductor where the magnetic field lines is measured.
(ii) direction of magnetic field lines produced by the straight carrying conductor :
If the direction of current is known then the direction of magnetic field produced by a state wire carrying current can be obtained by using Maxwell right hand thumb rule.
Maxwell right hand thumb rule is also known as Maxwell cork screw rule.
(iii) Ampere's swimming rule ( for needle deflection ) :
Imagine a man swimming along the wire in the direction of current in such a way that the current enter at his feet and leaves him at his hand facing toward a magnetic needles kept under Nick the wire then the magnetic field produced by the wire will be in such a way that the north pole of needle will be deflected towards his left hand.