MAGNETISM

PERMANENT MAGNETS

• A Permanent Magnet is magnetic almost forever (about 10,000 - 50,000 years).
• A Permanent Magnet has a magnetic field that causes magnetic moments in another magnetic object (metal) to create a temporary magnet.

ELECTROMAGNETS

• An Electromagnet is iron or steel core, Steel is much weaker. with coiled wire around it & when an electric current is put through it, it creates an Electromagnet.
• When the electric current is blocked (stopped) it is no longer a magnet, so it is very useful for jobs were you need to turn it on & off.
• Used in electric motors for cars and other machines.

TEMPORARY MAGNETS

• A Temporary magnet is a metal that is only magnetic when inside a magnetic field.
• A Temporary Magnet cannot attract or repel another Temporary Magnet.

SUPERCONDUCTORS

• Superconductors are very strong Electromagnets that can only repel other magnets.
• Created like an Electromagnet but instead of coiling wire around it coil aluminum, tin, or zinc.

LODESTONE

• Lodestone is a natural magnet made magnetic by the earth.
• It is believed that Lodestone was discovered by a Greek shepherd who was wearing lots of metal more than 4000 years ago.
• The scientific name for Lodestone is Magnetite.

MAGNETIC ATOMS

• The nucleus (centre) of an Atom is made of particles with a positive charge.
• Atoms have a magnetic moment, a tiny magnetic field that surrounds them.
• When Electrons spin around the Atom it creates an Electric charge, this charge creates a Magnetic Field.

MAGNETIC POLES

• All Magnets have a pole either North or South.
• A Opposite poles attract each other, and poles that are the same repel (A North Pole magnet attracts a South Pole magnet).
• Earth has magnetic poles too, the North magnetic pole is even located in Canada!

EARTH

• Earth is giant magnet, it has two poles, just like any other magnet.
• The magnetic field of Earth is 3 times stronger at the poles than in the centre!
• The Earth's poles have switched more than 400 time in the last 330 million years (north becomes south, south becomes north)
• Inside Earth is mostly melted iron and nickel.

CURIE TEMPERATURE

• Most magnets lose magnetism at the Curie Temperature.
• The Curie Temperature is different depending on the type of magnet.
• Magnets are stronger when they are cold.

CREATING MAGNETS

• To create a magnet you need to have all the magnetic moments in the metal to line up.
• Alnico (Aluminium, Nickel, Copper) is very helpful to do that if added to a metal to create a magnet.

COMPASSES

• A compass is magnetic tool used to find directions.
• The needle is magnetic and always points northern (the north magnetic pole) and points are added.
• It is made so which ever way the compass is pointing the needle will point the way your facing (north, south, east, or west).

MAGNETIC FIELDS

• The magnetic field is what attracts or repels for the magnet.
• It's size depends on the strength of the magnet.
• If another magnet (or metal if it is a metal it becomes a temporary magnet) is in that field it attracts or repels it.
• The field is stronger when it's closer to the magnet it's coming from.

HISTORY (1200S - 1840)

• 1200s - compasses first used by Europeans to navigate, first studies of magnets by Peter of Maricourt.
• 1600s - William Gilbert studies magnetism; writes book about his theory of earth being a giant magnet.
• 1700s - Charles Augustin de Coulomb discovers magnetic fields.
• 1830 - 1840 - Wilhelm Weber invents a way to test the strength of a magnetic field called the 'Weber' measurement.

HISTORY (1880 - 1930)

• 1883 - Nicola Tesla invents rotating magnetic field, used today in electric motors.
• 1895 - Pierre Curie discovers magnets lose magnetism at Curie Temperature.
• 1907 - Pierre Weiss discovers that when all magnetic moments line up it creates a magnet.
• 1928 - Ernst Ising and Werner Heisenberg discover that magnets are created by movement of electrons in atoms.

CONCULSION

• Magnetism is a very "cool" (slide 10), informational, interesting topic and is very fun to learn about!
• Please ask questions after the Kahoot!