1. Unit 6a: Intro to Magnetism

2. Magnetism and force between two charges are related—a result of the electromagnetic force

3. Magnetic Field
region of space surrounding a magnet that exerts a force on other magnets and magnetic material

4. Magnetic pole Regions of magnets that exert the strongest force
North and South pole—opposite ends
Two north poles or two south poles repel each other (like repels like)
A north pole is attracted to a south pole of another magnet

5. Field Lines of a magnet
the closer the lines are together, the stronger the magnetic field
Field lines point from north pole to south pole.
The direction of the arrow indicates the direction the north pole of magnetized object would align in the field
Field lines go from north to south

7. Earth’s Magnetic Field
produced by spinning of iron and nickel core.
Protects earth from solar winds which otherwise would strip the earth of the atmosphere

8. Earth’s Magnetic Field
Aurora in polar regions caused when magnetosphere is disturbed and charged solar particles interact with atmosphere

9. Earth’s Magnetic field
Earth’s geographic North pole is the magnetic south pole.—north pole of magnet points toward north

10. Earth’s Magnetic field
The magnetic poles move and reverse orientation about twice every 1 million years

11. Ferromagnetic material
Materials that can become magnetized are called ferromagnetic
Due to unpaired spin of electrons. (electrons usually are paired and have opposite spins)
Include metals iron, nickel, cobalt
Non-ferromagnetic materials-like aluminum-cannot interact with magnets

12. Ferromagnetic material
Materials that can become magnetized are called ferromagnetic
Ferromagnetic materials have regions, called domains, with magnetically aligned atoms with north and south poles
If the different domains are oriented randomly, they cancel out and there is no magnetic field
If the domains are mostly aligned, a material becomes magnetic

13. Magnetizing ferromagnetic material
When unmagnetized material becomes magnetized—domains reorient to become aligned
Often, once moved away from the magnet, the domains return to random orientation and object loses magnetic properties

14. Magnetizing ferromagnetic material
If domains remain aligned for any length of time once removed from close magnetic field, the object is described as a permanent magnet
Despite their name, permanent magnets can lose magnetic field over time (slow reorientation of domains through motion and vibrations in atoms)
Heating a permanent magnet will quicken the process of becoming unmagnetized