(i) Place the bar magnet on a sheet of white paper fixed on a drawing board. Mark the boundary of the magnet.
(ii) Place: the magnetic compass near the north pole of the given magnet.
(iii) Mark the position of two ends of the needle. Now move the needle to a new position such that its south pole occupies the position previously occupied by its north pole.
(iv) In this way proceed step by step till you reach the south pole of the given magnet.
(v) Join the point marked on the paper by a smooth curve. This curve represents a field line. Repeat the above steps for new positions of the compass needle.
