Define magnetic field lines. Describe an activity to draw a magnetic field line outside a bar magnet from one pole to another pole.
A magnetic field lines are lines which are drawn around the magnet and which always starts with the north pole and ending at the south pole.
> to draw a magnetic field line around the bar magnet.
> take a bar magnet and a compass and place them on a plane over a hard sheet.
> the boundary of the marker should be marked.
> Place the compass near the north pole of the magnet. The south pole of the needle points towards the north pole of the magnet. The north pole of the compass is directed away from the north pole of the magnet.
> mark the both end of the needle.
> now move the needle to a new position such that the previously occupied north position should now occupy the south position and vice versa.
> continue this process till you the south pole of the bar magnet.
> now by joining all the points by a curve will represent the magnetic field line.