Wikibooks: Electricity and magnetism/Magnetism

• Format: Book
• Language: English
• Subjects: North Pole; South Pole; South pole
• Online Access: https://en.wikibooks.org/wiki/Electricity_and_magnetism/Magnetism

= Magnets = Like electric forces magnetic forces obey the principle of the attraction of opposites. Magnets always have two poles a North Pole which is naturally attracted to the Earth s magnetic South Pole and a South Pole which is naturally attracted to the Earth s magnetic North Pole. In a compass the North Pole of the magnetic needle indicates the geographic North Pole of the Earth. The geographic North and South are therefore reversed in relation to the magnetic North and South. When magnets love each other they do this in a somewhat special way. The North Pole of one sticks to the South Pole of the other as if magnetism had chosen the eroticism of 69. Unlike electric forces isolated magnetic charges have never been found. Apparently Nature did not welcome magnetic monopoles. Magnets are always dipoles. If we cut a magnet in the middle between its two poles we do not obtain two monopoles but two new dipoles two new magnets which each have two poles It is explained by assuming that a magnetic material is composed of microscopic magnets all aligned in the same direction Magnetostatics is the study of magnetic forces between stationary magnets. The calculation of magnetic forces is similar to that of electric forces except that we reason on dipoles and never on monopoles Like the electric field \mathbf{E} for electric charges the magnetic field \mathbf{B} is like a mathematical intermediary that is used to calculate the forces between magnetized materials. It is also used to calculate the forces exerted by magnets on moving charges the forces exerted by moving charges on magnets and the forces exerted between moving charges. But it is also much more than a mathematical intermediary because it has an autonomous existence. = Magnetic force is produced by electric currents = A magnet naturally orients itself perpendicular to an electric current. Its direction depends on the direction of the current. An electric current is therefore a source of magnetic force. This is a discovery made by Hans Christian Ørsted in ...