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Magnetism

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Magnetism

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Magnetism

  1. 1. The ancient Greeks knew as well as we do that lodestone (an iron-rich mineral) could attract other pieces of iron. Magnesia Lodestone
  2. 2. Magnetism is an invisible force. This force pulls/attracts metal objects towards a magnet. horseshoe magnets bar magnets circular magnets. There are lots of different types of magnets (natural or man-made). Magnetite/ Lodestone
  3. 3. All magnets have two poles – a South pole and a North pole. North pole South pole North pole South pole North pole South pole
  4. 4. Poles that are different attract each other. This means the invisible magnetic force will pull the poles together like this.
  5. 5. Poles that are the same do not attract each other. These will repel. This means they will push each other apart and will not touch or attract each other at all. Attract and repel are opposites.
  6. 6. Some metals are magnetic. Objects made of these metals are attracted to a magnet. Just because an object is made from metal does not make it magnetic. This can is made from aluminium. Will it be attracted to the magnet if we put it underneath? The aluminium can is not attracted to the magnet. Aluminium is a metal but it is not magnetic.
  7. 7. Some metals are magnetic. Objects made of these metals are attracted to a magnet. Just because an object is made from metal does not make it magnetic. The nail is attracted to the magnet because iron is a magnetic metal. This nail is made from iron. Will this be attracted to the magnet if we put it underneath?
  8. 8. Let’s look at some other objects. Can you guess which ones will be magnetic? This knife is made of steel, which is magnetic. The pencil is not made from a magnetic material . This ball is made of rubber and is not magnetic. The screw is made from iron, just like the nail.
  9. 9. Are all magnets the same shape? No. There are lots of different types. Here are some of them. horseshoe magnets, bar magnets and… circular magnets.
  10. 10. What do all magnets have? All magnets have a North pole and a South pole. South pole North pole
  11. 11. What do different poles do ? Different poles attract.
  12. 12. What do poles that are the same do ? Poles that are the same repel.
  13. 13. Are all metals magnetic ? No. Only some metals are magnetic Aluminium is not magnetic. Iron, steel, nikel… are magnetics.
  14. 14. 4 things to know about magnet!!!!! 1. A magnet creates an invisible area of magnetism all around it called a magnetic field. 2. The north pole of a magnet points roughly toward Earth's north pole and vice-versa. That's because Earth itself contains magnetic materials and behaves like a gigantic magnet. 3. If you cut a bar magnet in half. You get two brand new, smaller magnets, each with its own north and south pole. 4. If you run a magnet a few times over an unmagnified piece of a magnetic material (such as an iron nail), you can convert it into a magnet as well. This is called magnetizationmagnetization..
  15. 15. Magnetic field Invisible area AROUND the magnet where it can attract a magnetic metal (apply its force). Outside it this force disappears. The magnetic field is stronger at the poles.
  16. 16. THE EARTH IS A HUGE MAGNET The Earth’s molten iron core acts like huge magnet The magnetic north pole is not the same than the geographical North Pole. GEOGRAPHICAL NORTH POLE MAGNETIC NORTH POLE
  17. 17. COMPASS Navigational instrument used in unknown terrains or when the visibility is poor, made up of: Magnetised Needle (point the magnetic north pole) The rose: circle around the needle marked with the cardinal points (N,S,W and E)
  18. 18. https://www.youtube.com/watch?v=_ygmHnjNYNo ELECTROMAGNETS Are objects that ACT like magnets when an electrical current passes through them. So the magnet is ONLY activated by electricity. If you switch off the electrical current the magnet stop working

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