Discovery and Applications of Electromagnetism

Watch a brief video about magnets here: http://www.youtube.com/watch?v=ak8Bh9Zka50

FERROMAGNETIC PARAMAGNETIC DIAMAGNETIC Materials may be classified as: FERROMAGNETIC strongly attracted to magnets iron, steel, cobalt, nickel PARAMAGNETIC slightly attracted by strong magnets wood, aluminum, platinum, oxygen DIAMAGNETIC slightly repelled by strong magnets zinc, bismuth, sodium chloride, water

Like poles repel; unlike poles attract. BASIC LAW OF MAGNETISM Like poles repel; unlike poles attract. Although it is possible to isolate positive and negative charges, it is impossible to isolate NORTH and SOUTH magnetic poles. Magnetic monopoles do not exist.

Include a variety of metal, plastic, and wooden objects. A common activity for young students is for them to be given a magnet and an assortment of materials, and for them to determine which materials are attracted to the magnet. Include a variety of metal, plastic, and wooden objects. Suggestions include: metal paper clips, plastic paper clips, pennies, nickels, dimes, quarters, aluminum foil, copper wire, soft drink cans, pencils, erasers, rulers, drink cups, balls, paper, cardboard, buttons, small toys, live plants, etc…

Click here to view some magnetic fields. Magnetic fields surround magnets. Field lines point from North to South outside the magnet. N S Click here to view some magnetic fields.

Magnetism is a property of charge in motion. Orbiting and spinning electrons (negative charges in motion) in the atom produce a magnetic field. The domain theory is used to explain why some materials are, or may become, magnetic. No one knows exactly why moving charges cause magnetism.

The north magnetic pole is not caused by protons, Even though magnetic properties are similar to electric properties, it is erroneous to directly relate positive and negative electric charges to north and south magnetic poles. The north magnetic pole is not caused by protons, nor is the south magnetic pole caused by electrons!!!!

In 1820, Danish physicist/ chemist Hans Christian Ørsted (Oersted) noticed that when current from his Voltaic pile was switched on and off, a compass needle placed near the wire deflected from true magnetic north. Within a few months of careful study, he deduced that a magnetic field circles a current-bearing wire.

You can replicate Oersted’s discovery by connecting wire to a battery and a switch. Place a compass underneath the wire such that the compass needle is directly in line with the wire above it. Observe the needle deflect when the current is switched on and off. Place the compass above the wire and make further observations. http://www.magnet.fsu.edu/education/tutorials/java/oersted/index.html

A magnetic field surrounds a current-bearing wire. The direction of the magnetic field can be determined by the “Right Hand Rule for a Current-Bearing Wire.” “Grasp wire with right hand so that thumb points in the direction of conventional (positive) current. Your fingers circle the wire in the direction of the magnetic field.”

This discovery, coupled with the knowledge that magnetic fields interact with other magnetic fields, quickly resulted in many important technological applications, including the electromagnet, the telegraph, and the electric motor. Google honors Oersted’s August 14 birthday in typical Google fashion.