What are magnets?
A magnet is an object that produces an invisible magnetic field. This magnetic field gives rise to a force that pulls on metals such as iron and nickel. The lines of force of the magnetic field exit from the north pole of the magnet and enter through its south pole.
The north pole of a magnet will always be attracted to the south pole of another magnet and will show repulsion to a north pole.
In Nature, you can find rocks that are naturally magnetic, so called lodestones. Lodestones are chunks of magnetite (Fe3O4) that have been exposed to the strong magnetic field from a bolt of lightning.
A compass is a magnet
By the 12th century, people had learned that by repeatedly rubbing a lodestone along an iron needle in one direction, they could create a compass. The compass needle aligns itself in the north-south direction, thanks to the fact that the Earth itself behaves like a giant magnet with a north pole and a south pole.
Can you really switch a magnet on and off?
The magnet in Mazenetics can be switch on an off by clicking the mouse button. This would not be possible with a permanent magnet, but it is indeed possible with an electromagnet, which is made from a coil of wire. When an electric current passes through it, the moving electrons give rise to a magnetic field, just like that surrounding a permanent magnet. When the electric current is switched off, the magnetic field disappears and the electromagnet stops acting as a magnet. Usually, an iron core is included in the coil which increases the magnetic field several hundred times!
Magnetic dipole moment: A spinning electron creates a magnetic moment which acts like a bar magnet (dipole).Every electron in every atom is a small magnet, since the electron spins around and creates a magnetic dipole moment. In most materials, however, the electrons have randomly oriented spins and there is thus no net magnetic field. In so called ferromagnetic materials, there is a long-range ordering phenomenon at the atomic level which causes electron spins to line up parallel with each other in a region called a domain.
Magnetic domains: Domains in a ferromagnetic material, randomly oriented (top) and aligned (bottom)In a piece of material these domains are oriented randomly so they cancel each other out, but in the presence of a magnetic field, for instance from a bar magnet, the domains align and the material is said to be magnetized. It has now become a magnet!
All permanent magnets, as well as the metals that are attracted to them, are ferromagnetic.
Other materials, such as water and wood, are usually not considered to be magnetic- but in fact, all materials are affected by magnets! For the ones that are not ferromagnetic, there is still another effect that is called diamagnetism, which causes the material to be weakly repelled by magnets. However, the effect is so weak that we don’t see it in everyday life.
See also
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(1 vote)  NewsCancer treatments can be delivered straight to tumour cells using tiny magnets.
[Guardian.co.uk]
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(2 votes) NewsThe human genome is all the DNA in each cell of our body - it holds the instructions for cells to grow and specialise until the many cells become... a human! So imagine how useful it...
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Mazenetics
Can you use magnetic force to guide the ball through the maze?
Instructions:
Mouse point and click to move the ball. You must click outside of the ball rolling area. Release mouse button to stop moving.
Article by Per Thorén, Chalmers University of Technology, Sweden
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