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Magnetism

Magnetism. Magnetism is the force of attraction or repulsion of a magnetic material due to the arrangement of its atoms, particularly its electrons. Lik e poles will repel, opposite poles will attract. Magnetic field lines describe the structure of magnetic fields in three dimensions.

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Magnetism

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  1. Magnetism • Magnetism is the force of attraction or repulsion of a magnetic material due to the arrangement of its atoms, particularly its electrons. • Like poles will repel, opposite poles will attract. • Magnetic field lines describe the structure of magnetic fields in three dimensions. • At the poles of a magnet, the magnetic field lines are closer together. • The strength of the magnetic field is greater where the lines are closer together and weaker where they are farther apart.

  2. Magnetic Domains • Moving electrons produce magnetic fields. • In most materials, these magnetic fields cancel one another and neutralize the overall magnetic effect. • In other materials, such as iron, cobalt, and nickel, the atoms behave as tiny magnets because of certain orientations of the electrons inside the atom. • These atoms are grouped in a tiny region called the magnetic domain.

  3. The Earth is a Magnet • It exerts a magnetic forces and is surrounded by a magnetic field that is strongest near the North and South magnetic poles. • The Earth’s magnetosphere extends far out into space and is constantly bombarded by magnetic particles from the sun – “solar wind”. • How to remove magnetism • Drop the magnet • Heat the magnet • The Curie point is the temperature at which the magnetic properties of a substance are removed and is different for each substance.

  4. Magnetic Fields Produced by Conductors And how to switch on and off the strangely attractiveness

  5. Oersted’s Discovery In 1819, the Danish physicist Hans Christian Oersted (1777-1851) discovered the connection between electricity and magnetism by accident while lecturing at the University of Copenhagen. He noticed that a compass needle placed closely to a current carrying wire would take up a position nearly perpendicular to the direction of the current.

  6. Magnetic Field of a Straight Conductor • The magnetic field lines for a straight conductor are concentric circles around the conductor.

  7. Parallel Wires

  8. How is the scrap metal held up by the crane?

  9. Electromagnets • A device that exerts a magnetic force using electricity. • The magnetic field around a straight conductor can be intensified by bending the wire into a loop.

  10. Coil or Solenoid • The magnetic field can be further intensified by combining the effects of a large number of loops would close together to form a coil, or solenoid.

  11. Parallel Coils

  12. Type of Core Material • The core material becomes an induced magnet, as its atomic dipoles align with the magnetic field of the coil. The core itself becomes an induced magnet. • The factor by which a core material increases the magnetic field strength is called the material’s relative magnetic permeability (K).

  13. Applications of Electromagnetism

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