• Take a small compass and a bar magnet.
• Place the magnet on a sheet of white paper fixed on a drawing board, using some adhesive material.
• Mark the boundary 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 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.
• In this way, proceed step by step until you reach the south pole of the magnet.
• Join the points marked on the paper by a smooth curve. This curve represents a field line.
• These lines represent the magnetic field around the magnet. These are known as magnetic field lines.
• Observe the deflection of the compass needle as you move it along the field line. The deflection increases as the needle is moved towards the pole.
