Form 3 PMR Science Chapter 7 Magnetism

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Form 3 PMR Science Chapter 7 Magnetism

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Form 3 PMR Science Chapter 7 Magnetism

  1. 1. CHAPTER 7 ELECTRICITYMagnetism
  2. 2. MAGNETIC MATERIALS
  3. 3. FERROMAGNETIC OBJECTS Objects which can be attracted to a magnet  Iron  Hematite  Magnetite  Nickel  Cobalt  Steel
  4. 4. NICKEL
  5. 5. COBALT
  6. 6. CHARACTERISTIC OF MAGNET
  7. 7. MAGNETIC FIELD Magnetic force of attraction works here Invisible to the eye Has Pattern and direction Shown by  Iron filings  Compass
  8. 8. GETTING MAGNETIC FIELD LINES
  9. 9. MAGNETIC FIELD LINES Begin – North pole End – South pole Do not cross one another Strongest – at Poles The stronger the magnetic field, the closer the magnetic field lines
  10. 10. DIRECTION OF MAGNETIC FIELD LINES
  11. 11. ELECTROMAGNETISM Magnetic effect of an electric current passing through a conductor Magnetic field is induced by the electric current
  12. 12. MAGNETIC FIELD AROUND A STRAIGHT WIRE Right hand grip rule tells us the direction of magnetic field Thumb >> current Fingers >> Direction of magnetic field
  13. 13. RIGHT HAND RULE
  14. 14. MAGNETIC FIELD OF SOLENOID Wire coiled around a conductor forms solenoid Called electromagnet
  15. 15. NORTH POLE – LEFT OR RIGHT?
  16. 16. NORTH POLE - TOP OR BOTTOM?
  17. 17. NORTH POLE – LEFT OR RIGHT?
  18. 18. ELECTROMAGNET Temporary magnet Magnetism (magnetic effect) – induced by electric current Direction of magnetic field >> determined by direction of electric current
  19. 19. SOLENOID - ELECTROMAGNET
  20. 20. STRENGTH OF ELECTROMAGNETIC FIELD Number of turns in the solenoid  The greater the number of turns, the stronger the electromagnetic field Amount of current  The greater the current, the stronger the magnetic field Hard iron core vs. Soft Iron core  Soft iron core produces stronger electromagnet
  21. 21. NUMBER OF TURNS
  22. 22. THE NORTH POLE OF A COMPASS NEEDLE IS AMAGNETIC NORTH POLE. IT IS ATTRACTED TO THEGEOGRAPHIC NORTH POLE, WHICH IS A MAGNETICSOUTH POLE (OPPOSITE MAGNETIC POLESATTRACT).

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