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Presentation on theme: "Magnetism."— Presentation transcript:

1 Magnetism

2 Properties of Magnets Magnetic – the ability to exert forces on magnets or other magnetic materials. Magnetic materials are affected by magnets but do not produce magnetism. Permanent magnet – a material that retains the magnetic properties even when no external energy is supplied.

3 Magnetic Pole Magnetic Pole – north or south; one of the two opposite places on a magnet where the magnetic field is the strongest; all magnets have at least one north pole and one south pole

4 The Magnetic Force Two magnets can either attract or repel. If two opposite poles face each other, the magnets attract. If two like poles face each other, the magnets repel. Most insulating materials are transparent to magnetic forces. Iron, cobalt, and nickel have strong magnetic properties.

5 The Magnetic Field Magnetic Field – the magnetic forces that surround an object at all points in space. Magnetic Field Line – one of many lines with arrows used to show the direction of the forces in a magnetic field. Magnetic field lines always point away from a magnet’s north pole and toward a magnet’s south pole.

6 Earth’s Magnetic Field
Earth, with its molten iron and nickel core, acts like as though a giant magnet buried deep inside, with the south pole end of the magnet located at the Geographic North Pole. The needle of a compass is a small permanent magnet and the North indicator (typically colored red or white) is a magnetic North Pole. The needle is free to rotate and will tend to align itself such that the North indicator points toward a magnetic South Pole. For example, in response to the Earth’s magnetic field, the compass will point toward the geographic North Pole of the Earth because it is in fact a magnetic South Pole.

7 Identifying Magnetic Field Lines
Because opposite poles (North-South) attract while similar poles (North-North or South-South) repel, the magnetic field lines of a bar magnet can be visualized using another magnet. A compass is an excellent tool for this.

8 Earth’s Magnetic Field and Space Radiation

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