* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Magnetism (High School)
Maxwell's equations wikipedia , lookup
Electromotive force wikipedia , lookup
Geomagnetic storm wikipedia , lookup
Edward Sabine wikipedia , lookup
Skin effect wikipedia , lookup
Mathematical descriptions of the electromagnetic field wikipedia , lookup
Friction-plate electromagnetic couplings wikipedia , lookup
Magnetic stripe card wikipedia , lookup
Giant magnetoresistance wikipedia , lookup
Magnetometer wikipedia , lookup
Neutron magnetic moment wikipedia , lookup
Electromagnetic field wikipedia , lookup
Magnetic monopole wikipedia , lookup
History of electromagnetic theory wikipedia , lookup
Earth's magnetic field wikipedia , lookup
Magnetotactic bacteria wikipedia , lookup
Electric machine wikipedia , lookup
Lorentz force wikipedia , lookup
History of electrochemistry wikipedia , lookup
Electromagnetism wikipedia , lookup
Magnetohydrodynamics wikipedia , lookup
Magnetoreception wikipedia , lookup
Magnetotellurics wikipedia , lookup
Multiferroics wikipedia , lookup
Magnetochemistry wikipedia , lookup
Eddy current wikipedia , lookup
Superconducting magnet wikipedia , lookup
Ferromagnetism wikipedia , lookup
Electromagnet wikipedia , lookup
Magnetism Properties of Magnets All magnets have two areas of strongest force, called poles. Each magnet has one north pole and one south pole. Like poles repel, and opposite poles attract. The magnetic region where you can “feel the force” is called a magnetic field. Magnetic Materials What makes some things magnetic, while other things can’t be magnetized? Spinning electrons cause small magnetic fields around each atom. Magnetic materials have atoms whose magnetic fields can be lined up in the same direction. Areas where atoms’ magnetic fields line up are called magnetic domains. magnetic domain Randomly arranged domains = No magnet! Magnetic domains lined up = Magnet! The Earth is a magnet! magnetic north pole geographic north pole magnetic south pole geographic south pole Magnetic lines of force around the earth are like the field lines around a giant bar magnet. The magnetic north pole and the geographic north pole are not located in the same place! The north pole of a compass points to the earth’s magnetic north pole. Electricity to Magnetism In 1820, H.C. Oersted discovered that an electric current flowing through a wire had a magnetic field around it. Electricity can cause magnetism! Electromagnets are powerful magnets that can be turned on and off. You can make an electromagnet stronger by (1) putting more turns of wire in the coil or (2) making a larger soft iron core, or (3) increasing the current through the wire. Uses for electromagnets A simple DC electric motor contains a permanent magnet, an electromagnet, and a commutator. When current flows through the electromagnet, it turns within the magnetic field of the permanent magnet, changing electricity to mechanical energy. Current meters also use permanent magnets and electromagnets. When current flows through a wire, it makes an electromagnet. The force between the electromagnet and the permanent magnet makes a needle move on the meter. Magnetism to Electricity Joseph Henry and Michael Faraday discovered that magnetism could also produce electric current. This is called If a magnet is moved back and forth through a coil of wire, current can be made to flow through the wire. This is the idea behind electric generators and transformers. Current moves left in wire. Current moves right in wire. electromagnetic induction. Uses for Electromagnetic Induction Generators produce AC current for home and industrial use. Water, wind, or steam are used to move large electromagnets through the coils of wire to produce current. Transformers are used to step up voltage of electricity that must travel long distances through wires. Other transformers then step down the voltage before it enters our homes.