about field lines allignment
When we place a bar magnet and we sprinkle the iron fillings around it.The iron fillings are arranged in a pattern because magnet exerts its influence in the region surrounding in it. Then the iron fillings experience its force and arranged themselves in a pattern. The magnet exerts forces surrounding in it this force we will call it as magnetic field. The lines arranged themselves in the pattern is called field lines. Magnetic field as both magnitude and directions . The directions can be shown by using the compass needle .This will help to show the directions. From this we will say that if we will place this near to the bar magnet its directions will be away from the north pole .So we can say that directions emerge at north pole and merge at south pole.We can also say that inside the bar magnet directions will be from south to north pole.No two field lines will cross each other.
