What would the world be like without magnetism?

1. What would the world be like without magnetism?

2. Magnets and Magnetic Fields Chapter 18 - Section 1 Pages 619-625

3. I. History of Magnetism • Magnets are named after a place called __________ (found in present-day ________) MAGNESIA GREECE • The iron-based mineral ___________ was used as a ____________ or “leading stone” almost ______ years ago. MAGNETITE LODESTONE 3,000 MAGNESIA

4. Lodestones were used to make primitive compasses

6. MAGNETISM- Background

7. II. Characteristics of magnets NORTH SOUTH Have a ________ and ________ pole (called a _________) DIPOLE 1. Similar to the “RULE OF CHARGES”, like poles _______, unlike poles __________. REPEL ATTRACT PAIRS 2. Always appear in _______. No matter how small the pieces of magnet are, each piece ALWAYS has ______ poles. TWO

9. FIELD Have a magnetic _______ = region where magnetic ________ may be detected FORCE POLES 1. Strongest near the ________. FIELD LINES 2. Represented by ______________ Demonstration: Iron filings and magnets *When sprinkled around a magnet, the iron filings line up with the magnetic field *Draw a diagram in your notes (include labels!)

15. III. What makes a magnet a magnet? A. Magnetic properties of a material depend on the motion of an atom’s ____________. The ____________ orbit the __________ of the atom and ______ like a top. ELECTRONS ELECTRONS NUCLEUS SPIN

16. e- B. This movement of the ___ creates _____________ around each individual atom MAGNETIC FIELDS • Electrons are in pairs. Electrons spin (in opposite directions up/down) and magnetic fields cancel each other not magnetic • When electrons ______________, magnetic fields ________________ creating a magnetic material! DO NOT HAVE A PAIR DON’T CANCEL OUT

17. Materials that can become magnetized are called _________________. FERROMAGNETIC • Include ______, _________, _________ IRON NICKEL COBALT • In these materials, _________________ of individual atoms are _____________________ to form a _____________________. MAGNETIC FIELDS GROUPED TOGETHER MAGNETIC DOMAIN • __________ form small, magnetized regions within the material DOMAINS

18. If the __________ are arranged randomly (in different ____________) the material is not a magnet. DOMAINS DIRECTIONS DOMAINS • If the ___________ are aligned (in the ______ direction) the material is a _________ SAME MAGNET

19. Magnetic fields of the domains line up to form a larger magnetic field

21. DOMAINS

22. Any piece of iron can become a magnet if placed in a magnetic field. The __________ will change orientation because of the ________________ and align. DOMAINS MAGNETIC FIELD

24. IV. Making / destroying a magnet Materials that are magnetic all of the time (like ____________) are called ____________ magnets. MAGNETITE PERMANENT B. _________________ materials may become magnets by: FERROMAGNETIC • __________________________________ Placing in a magnetic field (heating first is best) Stroking several times with a magnet • _______________________________ DOMAINS *both ways align the ___________ of the material

26. C. Magnets are weakened by: • _________________________________ Banging…hammering..etc…the magnet • __________________ Heating the magnet DOMAINS * ___________ are no longer aligned

27. V. The Earth as a Magnet Geographic North Pole The Earth and electrons are both magnets …sketch the Earth and its magnetic field in your notes. Magnetic South Pole

30. The Earth’s magnetic field protects us from solar radiation

32. AURORA BOREALIS AURORA AUSTRALIS

33. SUN SPOTS!

34. Next time: COMPASS ACTIVITY: How is a compass made? How does it work?

36. BIOMAGNETISM