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MAGNETISM

MAGNETISM. MAGNETISM. CAUTION BE CAREFUL WHERE YOU PLACE STRONG MAGNETS. MAGNETISM. MAGNETISM IS PRODUCED BY MOVING CHARGES. KEY TOPICS. MAGNETIC POLES & FORCES MAGNETIC MATERIALS MAGNETIC FIELDS ELECTROMAGNETS. MAGNETIC POLES.

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MAGNETISM

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  1. MAGNETISM

  2. MAGNETISM CAUTION BE CAREFUL WHERE YOU PLACE STRONG MAGNETS

  3. MAGNETISM MAGNETISM IS PRODUCED BY MOVING CHARGES.

  4. KEY TOPICS MAGNETIC POLES & FORCES MAGNETIC MATERIALS MAGNETIC FIELDS ELECTROMAGNETS

  5. MAGNETIC POLES THE “N” POLE OF A MAGNET MEANS THAT THIS POLE SEEKS THE NORTH POLE OF THE EARTH, IF THE MAGNET IS FREE TO ALLIGN ITSELF WITH THE EARTH’S MAGNETIC FIELD.

  6. LAWS OF ATTRACTION LIKE POLES REPEL UNLIKE POLES ATTRACT N S S N N S N S

  7. ACTIVITY • MAGNETIC COMPASS MAGIC • MAGNETIC POLE PALS • WATER COMPASS

  8. MAGNETIC POLES • A MAGNET IS A DIPOLE (TWO POLE). • THERE IS NO MONOPOLE (SINGLE POLE). • CUT A MAGNET IN HALF AND YOU GET TWO DIPOLES. N S N S N S

  9. PhET SIMULATION THE PhET SIMULATION “MAGNETS AND ELECTROMAGNETS” CAN BE USED TO SHOW THE POLES OF A MAGNET.

  10. ACTIVITY • MAGNETIC RECYCLE • SWEET TOOTH MAGNETS • MAGNETIC MINING

  11. MAGNETIC MATERIALS • MOST MATERIALS ARE NOT MAGNETIC • NATURALLY OCURRING MAGNETIC MATERIALS ARE CALLED FERROMAGNETIC (IRON-LIKE) • FERROMAGNETIC MATERIALS ARE • IRON • COBALT • NICKLE

  12. FERROMAGNETIC MATERIALS THE COMMON METALS, IRON, NICKEL AND COBALT ARE FERROMAGNETIC. THERE ARE TWO RARE EARTH ELEMENTS, GADOLINIUM AND DYSPROSIUM WHICH ALSO POSSESS THIS PROPERTY.

  13. Lodestone • A Lodestone is a naturally occurring piece of magnetic iron oxide. It is often bound in a brass frame, and is oriented to place the magnetic poles at the ends. • The word magnet comes from the region called Magnesia in Asia Minor. The word lodestone comes from the use of pieces of ore from Norway and Sweden which were suspended and used as guiding or leading stone; the Saxon word Læden means "to lead".

  14. FERROMAGNETISM • ELECTRONS HAVE MAGNETIC FIELDS DUE TO THEIR SPIN AND ORBITAL MOTION. • ATOMS OF FERROMAGNETIC MATERIALS POSSESS ELECTRONS WHICH HAVE MAGNETICS FIELDS THAT DO NOT CANCEL OUT INSIDE THE ATOM.

  15. MAGNETIC DOMAINS THESE ARE SMALL REGIONS IN A FERROMAGNETIC MATERIAL WHERE ALL THE MAGNETIC FIELDS OF THE ATOMS ARE ALIGNED.

  16. MAGNETIZATION IF THE DOMAINS ARE ALIGNED, THE MATERIAL IS POLARIZED AND BECOMES MAGNETIZED N S

  17. MAKING A MAGNET A PIECE OF “SOFT” IRON CAN BE MAGNETIZED BY RUBBING ONE END WITH ONE POLE OF A STRONG MAGNET.

  18. ACTIVITY • WATER COMPASS

  19. MAGNETIC FIELD • IMAGINARY LINES WHICH REPRESENT THE ALIGNMENT OF A MAGNET PLACED AT A POINT IN SPACE. • AN ARROW CAN BE DRAWN AT A POINT TO SHOW THE DIRECTION THAT THE “N” POLE POINTS • IF THERE ARE A GREATER NUMBER OF LINES IN AN AREA, THE FIELD IS STRONGER THERE. N S

  20. PhET SIMULATION THE PhET SIMULATION “MAGNETS AND ELECTROMAGNETS” CAN BE USED TO SHOW THE MAGNETIC FIELD NEAR A MAGNET.

  21. MAGNETIC FIELD • MAGNETIC FIELD LINES POINT TOWARDS THE “S” POLE OF A MAGNET. • MAGNETIC FIELD LINES POINT AWAY FROM “N” POLES N S

  22. EARTH’S MAGNETIC FIELD SINCE A NORTH SEEKING MAGNETIC POLE IS ATTRACTED TOWARDS THE EARTH’S MAGNETIC POLE LOCATED NEAR GREENLAND, THIS POLE MUST BE A MAGNETIC SOUTH POLE.

  23. EARTH’S MAGNETIC FIELD NORTH POLE S N SOUTH POLE

  24. EARTH’S MAGNETIC FIELD NORTH POLE S N SOUTH POLE

  25. PhET SIMULATION THE PhET SIMULATION “MAGNETS AND ELECTROMAGNETS” CAN BE USED TO SHOW THE MAGNETIC FIELD OF THE EARTH.

  26. MAGNETIC FIELD NEAR A WIRE THE FIELD NEAR A WIRE FORMS CIRCLES AROUND THE WIRE. MAGNETIC FIELD ELECTRON FLOW

  27. CHARGES MOVING IN CLOSED PATHS CREATE DIPOLE MAGNETIC FIELDS

  28. FIELD DUE TO A COIL CURRENT IN A COIL OF WIRE PRODUCES AN ELECTROMAGNET N S ELECTRON FLOW

  29. PhET SIMULATION THE PhET SIMULATION “MAGNETS AND ELECTROMAGNETS” CAN BE USED TO SHOW THE FIELD OF AN ELECTROMAGNET.

  30. ELECTROMAGNET A STRONG ELECTROMAGNET CAN BE PRODUCED BY USING A FERROMAGNETIC CORE.

  31. ACTIVITY • ELECTROMAGNET • OBSERVING MAGNETIC FIELDS WITH PHET

  32. FORCE ON A WIRE IF THE ELECTRONS IN A WIRE CROSS MAGNETIC FIELD LINES, THE WIRE WILL EXPERIENCE A NET FORCE. ELECTRONS FIELD FORCE N S

  33. ACTIVITY • FORCE ON A CURRENT CARRYING WIRE

  34. ELECTROMAGNETINDUCTION A VOLTAGE WILL BE INDUCED IN A COIL WHILE A MAGNETIC FIELD MOVES THROUGH THE COIL. V N S

  35. ACTIVITY • ELECTROMAGNETIC INDUCTION

  36. TRANSFORMER TWO COILS PLACED UPON A FERROMAGNETIC MATERIAL FORMS A TRANSFORMER. V

  37. ACTIVITY • TRANSFORMER

  38. SUMMARY • MAGNETIC POLES • NO MONOPOLES • MAGNETIC MATERIALS • FERROMAGNETISM • MAGNETIC FIELDS • EARTH’S MAGNETIC FIELD • ELECTROMAGNETS • FERROMAGNETIC CORE

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