Name: magnetic poles and everyday uses
Uploaded: 2023-04-30T12:40:25.000Z
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K12 Standards

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NC K-12 Science Standard Course of Study

9-12

Physical Science

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Motion and Stability- Forces and Interactions

PS.PSc.6.4

Magnetism

Le magnétisme a été observé pour la première fois il y a plus de 2500 ans près de l’ancienne ville de Magnésie.
Les aimants peuvent être trouvés dans des objets du quotidien comme les haut-parleurs, les cartes de crédit, les boussoles et les dispositifs de mémoire.
Un aimant à barres a un pôle nord et un pôle sud. Lorsqu’un clou en fer non magnétisé est mis en contact avec lui, il devient aimanté.
Comme les pôles d’un aimant se repoussent les uns les autres, tandis que les pôles différents s’attirent les uns les autres.
Les pôles d'un aimant ne peuvent pas être séparés en les brisant en deux morceaux. Au lieu de cela, des aimants plus petits, chacun avec une extrémité nord et une extrémité sud, sont obtenus. Par conséquent, les monopôles magnétiques ne sont jamais observés.
Dans une boussole de navigation, l’aiguille est une fine barre magnétique suspendue en son centre.
Le pôle nord d'une boussole est attiré près du pôle Nord géographique de la Terre.
La Terre agit également comme un énorme aimant en barre, avec son pôle sud magnétique près du pôle Nord géographique et son pôle nord magnétique près du pôle Sud géographique.
L’axe de l’aimant terrestre et l’axe géographique ne coïncident pas. Cette déviation est appelée déclinaison magnétique.

<ol>
	<li>OpenStax. (2019). Physique universitaire Vol. 2. [Version Web], section 11.1, pages 494-496. Récupéré de <a href="https://openstax.org/books/university-physics-volume-2/pages/11-1-magnetism-and-its-historical-discoveries">https://openstax.org/books/university-physics-volume-2/pages/11-1-magnetism-and-its-historical-discoveries</a></li>
</ol>

le magnétisme

Les aimants se trouvent couramment dans des objets du quotidien, tels que les jouets, les cintres, les ascenseurs, les sonnettes de porte et les dispositifs informatiques. Les expériences menées sur ces aimants montrent que tous les aimants ont deux pôles : l'un est étiqueté nord (N) et l'autre sud (S). Les pôles magnétiques se repoussent s'ils sont semblables et s'attirent s'ils sont différents. De plus, les deux pôles d'un aimant attirent des morceaux de fer non magnétisés.

Un pôle magnétique individuel ne peut pas être isolé. Peu importe sa taille, chaque morceau d'un aimant contient un pôle nord et un pôle sud. Cette propriété des aimants diffère de la propriété des charges électriques, dans laquelle des charges positives et négatives peuvent exister isolément.

Un exemple d'aimant est une aiguille de boussole. C'est un aimant en barre mince suspendu à son centre, de sorte qu'il est libre de tourner dans un plan horizontal. La Terre agit également comme un aimant géant, avec son pôle sud se dirigeant vers son pôle nord géographique. Le pôle nord d'une boussole est attiré vers le pôle nord géographique de la Terre parce que le pôle sud magnétique de la Terre est proche de son pôle nord géographique.

En 1819, le physicien danois Hans Oersted effectuait une démonstration en classe pour des étudiants et a remarqué qu'une aiguille de boussole bougeait lorsque du courant circulait dans un fil à proximité. Des investigations supplémentaires de ce phénomène ont convaincu Oersted qu'un courant électrique pouvait d'une manière ou d'une autre provoquer une force magnétique.

Aujourd'hui, le magnétisme joue de nombreux rôles importants dans nos vies. La compréhension des physiciens du magnétisme a permis le développement de technologies qui affectent à la fois les individus et la société. Par exemple, la tablette électronique dans le sac à main ou le sac à dos n'aurait pas été possible sans les applications du magnétisme et de l'électricité à petite échelle.

Tous les moteurs électriques contiennent des aimants. Les générateurs, qu'ils produisent de l'énergie hydroélectrique ou fassent fonctionner des feux de vélo, utilisent des champs magnétiques. Les installations de recyclage utilisent des aimants pour séparer le fer des autres déchets. La recherche sur l'utilisation de la magnétisation de fusion comme future source d'énergie se poursuit depuis plusieurs années. L'imagerie par résonance magnétique (IRM) est devenue un outil de diagnostic important dans le domaine de la médecine, et l'utilisation du magnétisme pour explorer l'activité cérébrale est un sujet de recherche et de développement contemporain. La liste des applications comprend également les disques durs d'ordinateurs, l'enregistrement sur bande, la détection d'amiante inhalé et la lévitation des trains à grande vitesse.

Le Magnétisme

Les aimants se trouvent couramment dans les objets du quotidien, tels que les jouets, les cintres, les ascenseurs, les sonnettes et les appareils informatiques. L’expérimentation sur ces aimants montre...

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magnetic poles and everyday uses

Magnetism appears in many everyday objects, from toys and hangers to elevators, doorbells, and computer devices. Magnets have two poles, called north and south. Like poles repel each other, while unlike poles attract. Both poles can also attract unmagnetized iron. A single magnetic pole cannot be isolated, because every part of a magnet contains both a north pole and a south pole.

A compass needle is a simple example of a magnet. It is a thin bar magnet suspended at its center, so it can turn freely in a horizontal plane. Earth also behaves like a giant magnet. Its south-seeking pole is near the geographic North Pole. That is why the north end of a compass points toward Earth’s geographic North Pole, which is close to Earth’s magnetic south pole.

The link between electricity and magnetism became clear in 1819. During a lecture demonstration, Danish physicist Hans Oersted noticed that a compass needle moved when current flowed in a nearby wire. Further study showed that an electric current can create a magnetic force. This discovery helped scientists connect electric currents with magnetic effects.

Magnetism is important in many modern technologies. Electric motors contain magnets, and generators use magnetic fields to produce power, including hydroelectric power and bicycle lights. Recycling facilities use magnets to separate iron from other waste. Magnetism also supports MRI, computer hard drives, tape recording, detection of inhaled asbestos, research on brain activity, and the levitation of high-speed trains. Work on magnetic containment for fusion energy is also ongoing.

Magnetic Poles and Everyday Uses

magnetism

Magnetism appears in many everyday objects, from toys and hangers to elevators, doorbells, and computer devices. Magnets have two poles, called north and south. Like poles repel each other, while unlike poles attract. Both poles can also attract unmagnetized iron. A single magnetic pole cannot be isolated, because every part of a magnet contains both a north pole and a south pole. A compass needle is a simple example of a magnet. It is a thin bar magnet suspended at its center, so it can turn...

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Magnetic force can balance the weight of a current-carrying wire when the wire sits in a magnetic field. Moving charges in the wire feel a force, so the wire itself can be pushed upward or downward. This example uses a flexible wire that is 40 cm long and has a mass of 10 g. It is held in a horizontal position inside a constant 0.40 T magnetic field. The goal is to find the current needed to remove the tension in the supporting leads. To do that, a free-body diagram is drawn first. The diagram...

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torque on a current loop in a magnetic field

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key terms and concepts

Learn how magnetic poles attract and repel, how compasses work, and how magnetism powers motors, generators, MRI, and more in everyday life.

Magnetic Poles and Everyday Uses | JoVE K12

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Magnetic Poles and Everyday Uses

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