Magnetic Field due to current in a Long straight Wire:



Prof. Hans oersted firstly described the magnetic field due to current in a wire in 1820.

Experiment:

  . Take a copper wire that passes vertically through a horizontal piece of card board.

  .  Place small magnet compass needles on the card board along a circle with centre at the wire.

    .  All the compass needles point in the direction of north south. when a heavy current through
  wire, the compass needles set themselves on the tangent to the circle.

   .  Reverse the direction of current, the direction of needles is also reversed.

   .   When the present through the wire is stopped, all the needles once more purpose within the
   north-south direction.

Conclusions:

 .   A magnet field is set up around current carrying conducter.

  .  The lines of forces or circular and their direction depends upon the direction of current.

 .   The magnet field lastes only as long as the current is flowing through it.

Direction of magnetic Field:

 . The direction of magnet field can be determined by ringht hand rule.

Direction Hand rule:

 .  If the wire is grasped in the fist of night hand with the thumb pointing in the direction
  of the current, then the curled fingers indicate the direction of magnetic field.