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MAGNETISM

MAGNETISM. MAGNETISM. Magnetic force : The force due to the spin on electrons in motion. Ferromagnetic - Strong magnetic attraction (most metals) Paramagnetic – Slight magnetic attraction (wood, oxygen) Diamagnetic - Repelled by magnetic

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MAGNETISM

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  1. MAGNETISM MAGNETISM

  2. Magnetic force: The force due to the spin on electrons in motion. Ferromagnetic- Strong magnetic attraction (most metals) Paramagnetic – Slight magnetic attraction (wood, oxygen) Diamagnetic- Repelled by magnetic force ( Zinc, Mercury)

  3. Magnetic Fields- Space around a magnet in which a magnetic force is exerted. Represented by magnetic field lines. * Field lines run from the north magnetic pole to the south magnetic pole Permeability- refers to the strength of the magnetic field. Where field lines are closer there is a higher permeability.

  4. PROPERTIES OF MAGNETS • Has polarity (North and South Pole) • Like poles repel, unlike poles attract. • Loadstone (magnetite) is a natural magnetic substance. • Iron, cobalt and nickel can be induced to have a magnetic field. • Most magnets are Al,Ni,Co (Alnico). Will hold field for a longer amount of time. • When a magnetic substance is near a magnetic field, it also acts as a magnet • A compass is a small magnet

  5. Earths magnetic field is due to the Earths’ iron core. Magnetic north is about 20˚ from geographic north. Magnetic pole can reverse. The last reversal was 700,000 years ago. Neutron star SGR1806-20 has a magnetic field 1 x 1015 times greater than the earths.

  6. DOMAIN THEORY The strength of a magnet depends tiny magnets called dipoles. As the dipoles line up, the material becomes magnetized. These dipoles are formed by the spin on the electrons.

  7. EFFECTS OF DOMAIN THEORY • Demagnetization- Dipoles become random when dropped or heated. • Reverse magnetization- If a weak magnet is placed in a stronger-reverse field, the dipoles of the weaker magnet will reverse. • Breaking a magnet produces two magnets with identical fields • Magnetic saturation occurs when all dipoles are aligned.

  8. Induced Magnetism- Electrons of a nonmagnetic substance align temporarily in a magnetic field. Occurs due to an electric current. Also called a temporary magnet.

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