Form 3 PMR Science Chapter 7 Magnetism

1. CHAPTER 7 ELECTRICITY
Magnetism

2. MAGNETIC MATERIALS

3. FERROMAGNETIC OBJECTS
 Objects which can be attracted to a magnet
 Iron
 Hematite
 Magnetite
 Nickel
 Cobalt
 Steel

4. NICKEL

5. COBALT

6. CHARACTERISTIC OF MAGNET

7. MAGNETIC FIELD
 Magnetic force of attraction works here
 Invisible to the eye
 Has Pattern and direction
 Shown by
 Iron filings
 Compass

8. GETTING MAGNETIC FIELD LINES

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

12. DIRECTION OF MAGNETIC FIELD LINES

13. ELECTROMAGNETISM
 Magnetic effect of an electric current passing
through a conductor
 Magnetic field is induced by the electric current

14. MAGNETIC FIELD AROUND A STRAIGHT WIRE
 Right hand grip rule tells us the direction of
magnetic field
 Thumb >> current
 Fingers >> Direction of magnetic field

15. RIGHT HAND RULE

17. MAGNETIC FIELD OF SOLENOID
 Wire coiled around a conductor forms solenoid
 Called electromagnet

18. NORTH POLE – LEFT OR RIGHT?

19. NORTH POLE - TOP OR BOTTOM?

20. NORTH POLE – LEFT OR RIGHT?

21. ELECTROMAGNET
 Temporary magnet
 Magnetism (magnetic effect) – induced by electric current
 Direction of magnetic field >> determined by direction of
electric current

22. SOLENOID - ELECTROMAGNET

23. 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

24. NUMBER OF TURNS

26. THE NORTH POLE OF A COMPASS NEEDLE IS A
MAGNETIC NORTH POLE. IT IS ATTRACTED TO THE
GEOGRAPHIC NORTH POLE, WHICH IS A MAGNETIC
SOUTH POLE (OPPOSITE MAGNETIC POLES
ATTRACT).