Strongest and Weakest Parts of a Magnet

Magnet with north and south poles marked laying next to a bed of quarters on a wooden table.

Kwanchai Lerttanapunyaporn/EyeEm/Getty Images

Did you know that the magnetic field of a magnet is not uniform? The strength of the field varies depending on its location around the magnet. The magnetic field of a bar magnet is strongest at either pole of the magnet. It is equally strong at the north pole when compared with the south pole. The force is weaker in the middle of the magnet and halfway between the pole and the center.

If you were to sprinkle iron filings on a piece of paper and place the magnet beneath it, you could see the path of the magnetic field lines. The field lines are closely packed at either pole of the magnet, widening as they get farther from the pole and connecting to the opposite pole of the magnet. The magnetic field lines emerge from the north pole and enter the south pole. The magnetic field gets weaker the farther you get from either pole, so a bar magnet is only useful for picking up small items over short distances.

Where Is the Magnetic Field Strongest?

Iron filings make a pattern tracing field lines because each bit of iron is itself a tiny dipole (the separation between magnetic fields). The force the dipole experiences is proportional to the strength of the dipole and proportional to 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. Because the magnetic field changes so dramatically, a dipole feels more force.

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Your Citation
Helmenstine, Anne Marie, Ph.D. "Strongest and Weakest Parts of a Magnet." ThoughtCo, Apr. 5, 2023, Helmenstine, Anne Marie, Ph.D. (2023, April 5). Strongest and Weakest Parts of a Magnet. Retrieved from Helmenstine, Anne Marie, Ph.D. "Strongest and Weakest Parts of a Magnet." ThoughtCo. (accessed June 10, 2023).