Magnet strength and magnetic field strength are not the same thing.
- Magnet strength measures how much magnetic force a magnet can exert on another magnet or a metal object.
- Magnetic field strength measures how strong the magnetic field is at a certain point in space.
The magnet strength is usually expressed in units of pull force or energy product.
The magnetic field strength depends on the distance from the magnet, the shape of the magnet, and the direction of the magnetic field.
The magnetic field strength is usually expressed in units of tesla (T) or gauss (G).
To illustrate the difference between magnet strength and magnetic field strength, consider two magnets of different sizes and shapes, but with the same grade (such as N52).
The grade indicates the maximum energy product of the magnet, which is a measure of how much magnetic energy it can store per unit volume.
The larger magnet will have more magnet strength than the smaller one, because it has more volume and can exert more force on another magnet or a metal object.
However, the magnetic field strength at a certain point near the magnets may not be proportional to their size or shape.
For example, if the larger magnet is a disc and the smaller one is a sphere, the disc magnet may have a higher magnetic field strength at its center than the sphere magnet, because the disc magnet has a larger surface area and a more concentrated magnetic field.
On the other hand, if the point is far away from both magnets, the magnetic field strength may be similar for both magnets, because the magnetic field decreases rapidly with distance.
Why some magnets are stronger
There are a few key reasons why some magnets have stronger magnetic force than others:
Different Materials
Magnets may look the same but be made of completely different materials like neodymium or ferrite. The material affects strength.
Grades
Within a material, there are grades from low to high strength. For neodymium, higher grades like N52 are stronger than lower grades like N35.
Size
Bigger magnets and thicker magnets (of the same size) have stronger force. Even a 0.5mm difference in a neodymium magnet’s thickness impacts strength.
Magnetization
The direction a magnet is magnetized in affects the magnetic force on each pole. If the intended pole is magnetized weakly, the overall strength will be reduced.
In summary, the key factors determining a magnet’s strength are the material, precise grade, dimensions/thickness, and proper magnetization. Considering these aspects helps explain why some magnets have greater magnetic force than others.