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9. Join the points marked on the paper by a smooth curve. This curve represents a
field line.
10. Repeat the above procedure and draw as many lines as you can. You will get a
pattern shown in Fig. 4. These lines represent the magnetic field around the
magnet. These are known as magnetic field lines.

Fig. 4 Field lines around a bar magnet

11. Observe the deflection in the compass needle as you move it along a field line.
The deflection increases as the needle is moved towards the poles.

Magnetic Field Lines

 Magnetic field surrounding the magnet and the force it exerts are depicted using
imaginary curved lines with arrow called magnetic field lines.

Properties of magnetic field lines

1. All field lines are closed curves.
2. Outside the magnet field lines emerge from North Pole and merge at South Pole.
3. Inside a magnet, the direction of field lines is from South Pole to its north pole.
4. Field lines never intersect each other.
5. Field lines are closed together near the poles and spread out away from them.
6. The field is stronger where the field lines are more closely spaced. So, the field is
stronger near the poles then at other points.
Why do field lines never intersect each other?
If two lines were to intersect each other, then a compass needle placed at the point of
interaction would point in two different directions which is not possible.

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