Show the pattern of magnetic field lines due to a bar magnet with the help of a diagram. (2)

Solution : 
 

Magnetic field lines are the imaginary curves represent the direction of magnetic field at a point in the vicinity of the magnet.

Below diagram shows some of the magnetic field lines patterns.

 
Above diagrams represents the magnetic field lines due to a single bar magnet placed in different orientation. In the below diagram the magnetic field lines due to two bar magnets is shown.



The magnetic field strength at any point is defined as the number of lines (called Magnetic Flux) per unit area.

So, if in a certain area lines are more, then the magnetic field strength will be more in that area.