1. Chapter 7 Magnetism

3. 7-1 – Magnetism Magnetism – Magnetic forces –
Magnetic poles produce magnetic forces
Forces based on
Strength of magnets
Distance between magnets
Like poles repel; opposite poles attract

4. 7-1 - Magnetism Magnetic field – Direction of field
Lines closer together versus farther apart
Why does magnetic field produced?

6. 7-1 - Magnetism Magnetic Field Direction
Always points away from north pole toward south pole

7. 7-1 - Magnetism Earth’s Magnetic Field
Earth’s magnetic poles are opposite to Earth’s geographic poles
What generates the Earth’s magnetic field?

8. 7-1 - Magnetism What makes a magnet? Magnetic domains –
Permanent magnets vs. temporary magnets

9. Magnetic poles cannot exist by themselves; north pole must have a south pole

10. 7-2 – Electricity and Magnetism
Electric Current and Magnetism
Electric current creates a magnetic field
Direction of current affects direction of magnetic field lines
Increasing current increases the strength of magnetic field
Magnetic field decreases as you move away from the wire

11. 7-2 – Electricity and Magnetism
Electromagnetism-
Electromagnetic force –
Electromagnets
Changing the shape of a current carrying wire changes the magnetic field
Forms a solenoid
More loops in solenoid, stronger the electromagnet

12. 7-2 – Electricity and Magnetism
Electromagnetism-
Electromagnetic force –
Electromagnets
Changing the shape of a current carrying wire changes the magnetic field
Forms a solenoid
More loops in solenoid, stronger the electromagnet

13. 7-2 – Electricity and Magnetism
Making an electromagnet rotate
Uses the magnetic field generated by current and the change in polarity

14. 7-2 – Electricity and Magnetism
Using Electromagnets
Speakers
Galvanometers
Electric Motors

15. 7-2 – Electricity and Magnetism
Electric Motors
See figure 15 on page 214
Uses the flow of current to change the poles of the electromagnet

16. 7-3 – Producing Electric Current
Electromagnetic Induction -
Uses a magnet to create electric current
Changing magnetic field

17. 7-3 – Producing Electric Current
Generators-
Uses electromagnetic induction
Turns mechanical energy into electrical energy

18. Motors and Generators Different sides of same coin
Motor = electrical energy in, mechanical energy out
Generator = mechanical energy in, electrical energy out

19. 7-3 – Producing Electric Current
Direct Current and Alternating Current
Direct Current (DC) –
Alternating Current (AC) –

20. 7-3 – Producing Electric Current
Transformers
Reduces voltage without changing amount of electrical energy