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Reinforce magnets
Permanent magnets can become weaker. There are several reasons for that. For example:
- Excessive temperature effects
- Too low temperature effects (especially for ferrite magnets, magnetic tapes, and magnetic foils)
- strong vibrations
- strong opposing magnetic fields
- oxidation
How can you strengthen magnets?
Magnets can be strengthened in different ways. For example, you can increase the number of magnets used and combine their magnetic fields into a stronger field. Ideally, the permanent magnets are stacked for this purpose. However, the number of stackable magnets is limited. Furthermore, only perfect stacks using uncoated individual magnets are suitable in order to achieve a higher adhesive force and to strengthen the newly created magnet. If the magnetic field is interrupted by irregularities and unevenness in the material, the field of such a stack is weaker than that of a single magnet of the same shape and size. To noticeably increase the magnetic force, the stack of disc magnets should also be no more than half the diameter of a single magnet.
If it is an electromagnet or a magnetic field generated by electricity, it can be strengthened by increasing the current strength as well as a higher number of applied coils turns. A particularly strong magnetic field is also obtained when a core made of soft iron is inserted into the current-carrying coil.
Alternatively, a horseshoe-shaped core or a core made of several iron bodies can be used to increase the attraction of the magnet. Such current-carrying magnets are also used in industry, medicine and in scrap yards because they can be controlled easily and specifically.
Is a magnet equally strong at every point?
To make a magnet, you first need a body made of a ferromagnetic material that is magnetized by applying a strong external magnetic field. The fact that both bodies are joined together also increases the existing magnetic force.
Inside the ferromagnetic object there are innumerable molecular magnets in a disordered structure, which are like microscopic bar magnets at the particle level. They are in groups in individual domains, the so-called Weiss districts, which in turn are aligned independently of one another. The effects of the individual magnetic fields existing in these associations cancel each other out due to the opposing orientations. If, for example, the north pole of an external magnet approaches the ferromagnetic body, all south poles of the elementary magnets turn towards it. The walls of the Weiss domains become smaller, fold over, and allow the molecular magnets to be aligned evenly. Correspondingly, magnetic poles are formed at both ends of the body - a south pole pointing in the direction of the external magnetic field and a north pole on the opposite side. The newly created magnet is strongest at these poles. This becomes visible when you place a sheet of paper on the magnet, add iron filings and gently shake the sheet. The chips depict the field lines, which in turn are an indicator of the strength and direction of the magnetic force. The lines enter the magnet at the south pole, run from there to the north pole and exit there again. Here they continue their way back to the South Pole. Due to the prevailing repulsive forces, they run parallel to one another and accordingly in curved lines. It can be seen that most of the iron filings are deposited at the poles, whereas the lowest concentration of field lines or flux density is present in the center of the magnet and consequently the lowest force prevails.