This document discusses magnetism and electromagnetism. It explains that ferromagnetic objects like iron, nickel, and cobalt can be attracted to magnets. It describes magnetic fields and field lines, and how they behave and can be visualized. It also discusses how electric currents can induce magnetic fields based on the right hand rule, including around wires and in solenoids. The strength of electromagnetic fields depends on factors like the number of turns in a solenoid and the current.

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).