Properties of Magnetic Field Lines | What are Magnetic Field Lines
Properties of Magnetic Field Lines | What are Magnetic Field Lines :- Just as electric field lines graphically represent the field around an electric charge, in the same way magnetic field lines are drawn to graphically represent the magnetic field around a magnet.
We can draw magnetic field lines based on the patterns made of iron filings around a bar magnet. To draw magnetic lines we use magnetic dipoles (small compass needles).
Properties of Magnetic Field Lines
1. A tangent line drawn at a point on the magnetic field line gives the direction of the resultant magnetic field at that point.
The tangent line drawn at point P in red colour on the above magnetic field line expresses the magnetic field 
2. Two magnetic field lines never intersect each other, because if they intersect then two tangent lines can be drawn at the intersection point which will show the two directions of the magnetic field at the same point. This means that if a compass needle is placed at the intersection point, it will point in two directions and this is not possible.
3. The magnetic field lines of a bar magnet or a current carrying solenoid always form a continuous closed loop. These are not like the electric field lines of an electric dipole which start from a positive charge and end at a negative charge or start from a positive charge and go towards infinity or start from infinity and end at a negative charge.
4. The denser the magnetic field lines are, the stronger is the magnetic field at that place. The more field lines passing through a unit area of a plane perpendicular to the magnetic field, the stronger is the magnetic field at that location. In the above figure the magnetic field near loop L1 is stronger than that near loop L2.
5. Magnetic field lines always exert lateral pressure on each other, due to which there is always repulsion between the two lines.