Magnetic lines of force are the imaginary lines that are used to illustrate and describe the pattern of the magnetic field. These lines travel from the north pole to south pole outside the magnet body. These lines travel from the south pole to north pole inside the magnet body. A magnetic field is represented with the help of magnetic lines of force. These lines are also known as magnetic field lines. Fig. 1 depicts the magnetic field lines of a bar magnet.
Properties of Magnetic lines of force
1. These lines are continuous and closed curves that travel from the north pole of a magnet, then pass through the surrounding space and then arrive at the South Pole. These lines travel from the south pole to north pole inside the magnet.
2. A tangent at any point on the magnetic lines of force gives the direction of the magnetic flux density (B).
3. The density of magnetic lines of force gives the magnitude of the magnetic flux density (B). It means that closely spaced lines represent a strong magnetic field and widely spaced lines represent a strong magnetic field.
4. Two magnetic lines of force do not intersect each other. If they intersect each other, it means that at intersection point, there will be two directions of the magnetic field and this is not possible.
5. Magnetic lines of force contract longitudinally buy they dilate laterally.
6. These lines are not real lines but are imaginary lines.
If they are only imaginary, then how can the strength of anything be measured by their number? How do you count them? As you count sheep?