The lines of force are the imaginary curves through which a magnet is supposed to act as shown in Fig. 11.11.
It can otherwise be defined as the path along which a unit north pole would move if it is free to move.
OR
It is that imaginary curve, the tangent on which indicates the direction of field. It’s unit is maxwell and lines.
Fig. 11.11. Magnetic field
What are the properties of the lines of force?
Following are the properties of the magnetic lines of force:
- All the lines of force starts from the north pole and terminate to south pole outside the magnet and from south to north inside the magnet.
- There is no perfect insulator for the lines of force.
- All thé lines of force try to follow the shortest path and exhibit the elastic nature.
- The lines of force do not cross each other.
- It produces the effect of magnetic shielding if a closed magnetic ring is placed between two poles the maximum lines of force will complete its path through the ring and a minimum through the air.
- The magnetic lines of force produces the induction effect. As the soft iron bar magnetises when the permanent magnet is brought near it as shown in Fig. 11.5.Fig. 11,5.
State the care and maintenance of the permanent magnet?
If the molecules of the permanent magnet are de-arranged then the magnet is demagnetised so the following precautions should be taken:
(i) It should be used properly and should not be thrown.
(ii) It should not be heated up.
(iii) It should not be hammered.
(iv) If a pair of magnets is kept, the keepers should be used and magnets should be kept facing the opposite polarity.