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natural Hans Christian Oersted He discovered that electric current produces a magnetic force. He couldn’t explain the phenomenon. Two other scientists investigated further… André-Marie Ampere He decided to study the relationship between electricity and magnetism. He discovered the electron (he called it the ‘electrodynamic molecule’). Michael Faraday He showed that by moving a loop of wire over a magnet, an electric current is produced in the wire. A changing magnetic field produces an electric field. He called this the ‘electromagnetic rotary device’ Dynamo (electric motor) Bar magnet Permanent magnets: they always have a magnetic field. They have TWO POLES: NORTH & SOUTH. They attract some metals: iron, steel… They attract or repel other magnets. Magnets attract and repel Like poles repel… …unlike poles attract. The Earth’s magnetic field Magnetosphere – from the South Pole to the North Pole. North Pole of the Earth = south pole of the magnetosphere The effects of electricity Thermal energy The amount of thermal energy depends on the substance. As electric current travels through a copper wire, very little thermal energy is produced. However, in an oven, electric current passes through a substance that produces a lot of thermal energy. The effects of electricity Chemical reactions Electrolysis is a chemical reaction that is produced when an electric current flows through a liquid solution of charged particles. The positively charged atoms in the solution are attracted to the negative electrode. They gain electrons. Negatively charged atoms are attracted to the positive electrode. They lose electrons. The solution is transformed into two separate substances. Uses of electromagnets Electric bell 1. The switch is closed and electric current flows through the circuit. 2. The current produces a magnetic field in the electromagnet. 3. The hammer is attracted to the electromagnet and hits the bell. 4. The movement of the hammer breaks the circuit, and the hammer returns to its original position. Then the cycle begins again. Uses of electromagnets Maglev – magnetic levitation train 1. The Maglev has magnets in the base of the train. 2. The tracks have magnets at either side. 3. The lower magnets are positioned so that they will repel the magnets in the train, causing the train to levitate above the track. 4. The magnets above and in front of the train attract the magnets in the train, causing the train to move forward.