- The field in between north and south pole of horseshoe magnet are straight and parallel.
- If the wire is passing perpendicular to the paper, the magnetic lines of force are concentric circles, when the current is passed.
- The direction of field lines due to the wire in upper part coincides with the direction of field lines of horseshoe magnet.
- The direction of field lines by the wire in lower part is opposite to the direction of field lines of horseshoe magnet.
- Hence the net field in upper part is strong and in the lower part is weak.
- Hence a non-uniform field is created around the wire.