Question

Where are the field lines most concentrated around a bar magnet?

• A. At the North Pole.
• B. At the centre.
• C. At both poles.
• D. At the South Pole.

Answer 1

Answer: (C)

At both poles are the field lines most concentrated around a bar magnet

Iron filings make a pattern tracing field lines because each bit of iron is itself a tiny dipole. The force the dipole experiences is proportional to the strength of the dipole and the rate at which the magnetic field changes. The dipole tries to align itself with a magnetic field, but at the ends of a bar magnet, the field lines are very close together. What this indicates is that the magnetic field varies strongly over a short distance compared to the variation closer to the middle of the magnet.