1. Electricity & Magnetism

2. A quick review of what we’ve learned… through videos!

3. Relating Electricity & Magnetism
Watch this video. Create some hypotheses to explain what you saw.

4. Relating Electricity & Magnetism
Under what conditions did the wire jump?
Are stationary electric charges affected by magnetic fields?
What about moving electric charges?

5. Relating Electricity & Magnetism
How can we explain this behavior thinking about magnetic fields?
Pg. 563, Figure 2

6. Motor Principle
A current-carrying conductor crossing an external magnetic field, experiences a force perpendicular to the magnetic field and the direction of the current.
Current flows from positive to negative

7. Motor Principle Right Hand Rule #3
Thumb in direction of conventional current
Fingers in direction of magnetic field
Palm facing direction of force
Current flows from positive to negative

8. Practice
Determine the direction of the force on the conductor:

9. Motor Parts of a Motor Cell – Provides current
Field magnet – Provides external magnetic field
Coil - Part of the motor that rotates (armature)
Commutator – “Split ring” that rotates with the coil
Brushes – Connects commutator and cell

10. Motor Principle
For a motor to turn continuously, the current must change direction in the loop. In a DC or direct-current motor, this is accomplished with brushes & the split-ring commutator

11. Parts of a Motor
Name the parts of the motor that are labelled in the diagrams below!

12. Motor Principle

13. Motor Principle

14. Motor

15. Motor Principle

16. Motor

17. Motor

18. Motor

19. Homework
Pg. 566 #1, 2
Pg. 571 #1, 2