1. Notes: 16.2
The source of Magnetism

2. Electricity & Magnetism -Current flowing through a wire
generates a magnetic field around that wire
Electromagnet- magnet created by current flowing
through wires

3. Magnetic field direction- determined by the “right hand rule” for both a single wire and a coil of wires
Single wire- thumb points in direction of current, fingers point in direction of mag. field

4. Coil – fingers point in direction of current flow,
thumb points in the North direction

5. Electromagnet advantages- can switch on/off, can switch directions of poles, can alter field strength with more/less current so they can be VERY strong
Uses: doorbell, toaster, electric motors

6. Factors effecting an electromagnet- *Amount of current *Core material
*Number of turns
Magnet shape, size and winding pattern also effect the field*

7. The Walker magnet, weighs 88tons, listed by Guinness as the largest of its kind,
has enormous power -- about 270 tons of lifting capacity. It removes iron from Copper ore in mining operations.

8. All magnetism comes from electric currents
Diamagnetic- individual electrons in each atom cancel each other out, so no magnetic field in these materials (lead & diamond)
Paramagnetic- each atom has a magnetic field, but the atoms line up to cancel each other out, so not magnetic field (aluminum is an example, but it does have a very weak magnetic field)

9. Ferromagnetic- material with strong magnetic properties
Aligned magnetic domain- each atom’s electrons align with other atoms electrons to increase the total magnetic field strength

10. Soft magnet –easy to magnetize, but looses its magnetic field easily (steel)
Hard Magnet- domains of hard magnets stay aligned for a long time (nickel, cobalt, neodymium)
Heat, shock and other magnets can demagnetize a magnet field
Liquids and gasses are not permanent magnets as electrons do not stay aligned