How can something be magnetized

When particles from the solar wind hit atoms of gas in the upper atmosphere around the geomagnetic poles, they produce light displays called aurora s. Historic Directions The ancient Greeks and Chinese knew about naturally magnetic stones called "lodestones. The Chinese discovered that they could make a needle magnetic by stroking it against a lodestone, and that the needle would point north-south. Animal Magnetism Some animals, such as pigeons, bees, and salmon, can detect the Earth's magnetic field and use it to navigate.

Scientists aren't sure how they do this, but these creatures seem to have magnetic material in their bodies that acts like a compass. The bright bands of color around the North Pole caused by the solar wind and the Earth's magnetic field.

Also known as the aurora australis. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited. Caryl-Sue, National Geographic Society. Dunn, Margery G. For information on user permissions, please read our Terms of Service.

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If no button appears, you cannot download or save the media. Text on this page is printable and can be used according to our Terms of Service. Ferromagnetic materials have minute magnetic domains created within their atomic structure.

These domains can be viewed as very small bar magnets with north and south poles. When the material is not exposed to an external magnetic field, the magnetic domains are randomly oriented.

When a material is placed in a magnetic field, the domains align themselves. Thus, the object itself effectively becomes a magnet. From the study of magnetic fields produced by bar magnets and moving charges, i. It is observed that the field of a long bar magnet is like the filed produced by a long solenoid carrying current and the field of the short bar magnet resembles that of a single loop. This similarity between the fields produced by magnets and current urges an enquiring mind to think that all magnetic effects may be due to circulating currents i.

The magnetism produced by electrons within an atom can arise from two motions. First, each each electron orbiting the nucleus behaves like an atomic sized loop of current that generates a small magnetic field; the situation is similar to the field created created by the current loop, each electron possesses a spin that also gives rise to a magnetic field.

The net magnetic created by the electrons within an atom is due to the combined field created by their orbital and spin motions. Since there are a number of electrons in an atom, there current of spins may be so oriented of aligned as to cancel the magnetic effects mutually or strengthen the effects of each other. An atom in which there is a resultant magnetic filed, behaves like a tiny magnet and is called magnetic dipole. The magnetic fields of the atoms are responsible for the magnetic behaviour of the substance made up of these atoms.

Magnetism is, therefore, due to the spin and orbital motion of the electrons surrounding the nucleus and is thus a property of all substance. It may be mentioned that the charged nucleus itself spins giving rise to a magnetic filed.

However, it is much weaker than that of the orbital electrons. Pyrolytic carbon, a substance similar to graphite, shows even stronger diamagnetism than bismuth, albeit only along one axis, and can actually be levitated above a super-strong rare earth magnet. Certain superconducting materials show even stronger diamagnetism below their critical temperature and so rare-earth magnets can be levitated above them.

In theory, because of their mutual repulsion, one can be levitated above the other. Paramagnetism occurs when a material becomes magnetic temporarily when placed in a magnetic field and reverts to its nonmagnetic state as soon as the external field is removed. When a magnetic field is applied, some of the unpaired electron spins align themselves with the field and overwhelm the opposite force produced by diamagnetism.

However, the effect is only noticeable at very low temperatures, according to Daniel Marsh, a professor of physics at Missouri Southern State University. Other, more complex, forms include antiferromagnetism, in which the magnetic fields of atoms or molecules align next to each other; and spin glass behavior, which involve both ferromagnetic and antiferromagnetic interactions.

Additionally, ferrimagnetism can be thought of as a combination of ferromagnetism and antiferromagnetism due to many similarities shared among them, but it still has its own uniqueness, according to the University of California, Davis. When a wire is moved in a magnetic field, the field induces a current in the wire. Conversely, a magnetic field is produced by an electric charge in motion. A charge moving in a straight line, as through a straight wire, generates a magnetic field that spirals around the wire.

When that wire is formed into a loop, the field becomes a doughnut shape, or a torus. According to the Magnetic Recording Handbook Springer, by Marvin Cameras, this magnetic field can be greatly enhanced by placing a ferromagnetic metal core inside the coil.

In some applications, direct current is used to produce a constant field in one direction that can be switched on and off with the current. This field can then deflect a movable iron lever causing an audible click.

This is the basis for the telegraph , invented in the s by Samuel F. They are everywhere from physics laboratories to compasses used for camping trips to souvenirs stuck on refrigerators.

Some materials are more susceptible to magnetism than others. Some types of magnets, such as electromagnets, can be turned on and off while permanent magnets produce a steady magnetic field all the time.

All materials are made up of magnetic domains. These are tiny pockets that contain atomic dipoles. When these dipoles become aligned in a single direction, the material exhibits magnetic properties. Iron in particular is an element whose dipoles are easily aligned. In other materials, dipoles can be aligned within a domain but not with respect to other domains in the same piece of material. These domains can be detected using a process called magnetic force microscopy.

When a material is placed in a strong magnetic field, its domains will align and the material itself will become magnetized.