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Do Now Given the following objects, a piece of aluminum foil, a nickel, a plastic figure, a piece of wood, a glass vase, and some paper clips, predict which objects will be attracted to a magnet. How do you know? Magnetism repulsion – force of attraction or • not all objects are affected by the force of magnetism ex. wood, glass, paper, plastic • common metals affected by magnetism are iron, nickel, and cobalt They have a south pole. They have a north pole. • The north and south pole are forces that act on each other. They are surrounded by a magnetic field. • Magnetic Poles are points on a magnet that have opposite magnetic qualities. • North and South The pole of a magnet that points to the north is called the magnet’s north pole. The opposite end of the magnet, called the south pole, points to the south. the north pole of a magnet points North • it is often called “North-seeking” like magnetic poles repel each other unlike if magnetic poles attract each other the north pole of one magnet is brought near the north pole of another magnet, they will repel each other if two south poles are brought together, they will repel each other • Magnetic Forces When you bring two magnets close together, the magnets each exert a magnetic force on the other. These magnetic forces result from spinning electric charges in the magnets. The force can either push the magnets apart of pull them together. Magnetic Fields A magnetic field exists in the region around a magnet in which magnetic forces can act. Atoms and Domains In materials such as iron, nickel, and cobalt, groups of atoms are in tiny areas called domains. The north and south poles of the atoms in a domain line up and make a strong magnetic field. • Losing Alignment When domains move, the magnet is demagnetized, or loses its magnetic properties. • Making Magnets You can make a magnet from demagnetized material if you line up its domains with another magnet. Cutting a Magnet When you cut a magnet in half, you end up with two magnets. • Atoms and Domains Some magnets, called ferromagnets, are made of iron, nickel, cobalt, or mixtures of those metals. Another kind of magnet is the electromagnet. This is a magnet made by an electric current. • Temporary and Permanent Magnets Temporary magnets are made from materials that are easy to magnetize. But they tend to lose their magnetization easily. Permanent magnets are difficult to magnetize, but tend to keep their magnetic properties longer. magnetic induction – process by which a material can be made into a magnet. some materials are easy to magnetize • ex. iron a material that is easily magnetized tends to lose its magnetism quickly a magnet made of this kind of material is called a temporary magnet materials that are hard to magnetize will also stay magnetized for a long time a magnet that is hard to magnetize but tends to keep its magnetism is called a permanent magnet. • One Giant Magnet Earth behaves as if it has a bar magnet running through its center. • Poles of a Compass Needle The point of a compass needle is attracted to the south pole of a magnet. Opposite poles of magnets attract each other. • South Magnetic Pole near North Geographic Pole A compass needle points north because the magnetic pole of Earth that is closest to the geographic North Pole is a magnetic south pole • The Core of the Matter Scientists think that the Earth’s magnetic field is made by the movement of electric charges in the Earth’s core. • A Magnetic Light Show Earth’s magnetic field plays a part in making auroras. An aurora is formed when charged particles from the sun hit oxygen and nitrogen atoms in the air. Magnetic Force and Electric Current An electric current can cause a compass needle to move. The needle is a small magnet. This property is useful in electric motors. Aurora Borealis Aurora Australis