(N/A) Magnetic field is the region around a magnet where the magnetic force can be experienced.
Activity:
$1$. Fix a sheet of white paper on a drawing board using adhesive material.
$2$. Place a bar magnet in the center of the paper and mark its boundary.
$3$. Place a small compass near the north pole of the magnet. The south pole of the compass needle will point towards the north pole of the magnet,and the north pole of the needle will point away from it.
$4$. Mark the positions of the two ends of the compass needle.
$5$. Move the compass to a new position such that its south pole occupies the position previously occupied by its north pole.
$6$. Repeat this process step by step until you reach the south pole of the magnet.
$7$. Join the points marked on the paper to obtain a smooth curve,which represents a magnetic field line.