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In the previous sections, we have learned about magnetic fields in detail. In this session, with the help of an activity, we will draw the field lines of a bar magnet.
  • Set a sheet of white paper on a drawing board using some sticky material.
  • Locate a bar magnet in the centre of the paper.
  • Spray some iron filings evenly around the bar magnet, as shown in the below figure. You may use a salt sprinkler for this purpose.
  • Now, tap the board mildly.
What do you observe?
The iron filings organise themselves in a pattern, as shown in the below figure.
Iron filings tracing the magnetic field of a bar magnet
Magnetic field is shown by iron filings
Why do the iron filings arrange in such a pattern? What does this pattern illustrate?
The magnet exerts its impact in the area surrounding it. Therefore, the iron filings experience a force. The force thus exerted makes iron filings order in a pattern. The area surrounding a magnet (where the magnet's force can be recognised) has a magnetic field. The lines along which the iron filings arrange themselves denote magnetic field lines.
Are there any different ways of obtaining magnetic field lines around a bar magnet?

Yes. You can draw yourself the field lines of a bar magnet.
In the upcoming sections, we will do an activity to draw the field lines of a bar magnet by ourselves.