## Magnetic Field and Field Lines

Danish physicist, H. C. Oersted observed during the course of a Lecture that there is a connection between current and magnetism. We will study magnetic fields and also about electromagnets and electric motors which involve the magnetic effect of electric current, and electric generators which involve the electric effect of moving magnets.

A compass needle is a small bar magnet whose ends point approximately towards north and south directions. The end pointing towards the north is called north seeking or north pole. The other end that points towards the south is called south seeking or south pole.

Example 1.
Why does a compass needle get deflected when brought near a bar magnet?
When a compass needle is brought near a bar magnet, it gets deflected as a force of attrac¬tion or repulsion acts between the bar magnet and the compass needle.

## Magnetic Field

It is defined as the region around a magnet in which the force of attraction and repulsion can be detected.

## Magnetic Field Lines

These are imaginary lines drawn around a magnet that describe the magnetic field around a magnet and indicate the direction in which a hypothetical North pole would move if placed at that point.

Characteristics of Magnetic Lines of Force

1. The magnetic lines of force indicate the direction in which an N-pole would move if placed at that point.
2. The relative strength of the magnetic field is shown by the degree of closeness of the field lines.
3. No two lines of force intersect each other, for if they did, it would mean that there would be two directions of magnetic field at the point of intersection.
4. The direction of magnetic field at any point is found by drawing a tangent at that point.

Example 2.
Why don’t two magnetic lines of force intersect each other?