1. Physics for Scientists and Engineers II, Summer Semester 2009 1 Lecture 12: June 17 th 2009 Physics for Scientists and Engineers II

2. Physics for Scientists and Engineers II, Summer Semester 2009 2 The Hall Effect d t y x z + - When positive charge carriers contribute to current I: Positive charges are deflected up. When negative charge carriers contribute to current I: Negative charges are deflected up.

3. Physics for Scientists and Engineers II, Summer Semester 2009 3 The Hall Effect (for Positive Charge Carriers) d t y x z + + + + + - - - -

4. Physics for Scientists and Engineers II, Summer Semester 2009 4 The Hall Effect – what you can get from it.

5. Physics for Scientists and Engineers II, Summer Semester 2009 5 History

6. Physics for Scientists and Engineers II, Summer Semester 2009 6 The Biot-Savart Law

7. Physics for Scientists and Engineers II, Summer Semester 2009 7 An Example: Calculate the Magnetic Field at the Center of a Circular Conductor Carrying a Current I x y z

8. Physics for Scientists and Engineers II, Summer Semester 2009 8 An Example: Calculate the Magnetic Field at the Center of a Semicircular Conductor Carrying a Current I x y z Infinitely long straight sections

9. Physics for Scientists and Engineers II, Summer Semester 2009 9 An Example: Calculate the Magnetic Field at Point P x y z

10. Physics for Scientists and Engineers II, Summer Semester 2009 10 An Example:

11. Physics for Scientists and Engineers II, Summer Semester 2009 11 An Example: Calculate the Magnetic Field at Point P x y z

12. Physics for Scientists and Engineers II, Summer Semester 2009 12 Magnetic Force Between Two Parallel Conductors

13. Physics for Scientists and Engineers II, Summer Semester 2009 13 Now Place a Second Current Parallel to it…..

14. Physics for Scientists and Engineers II, Summer Semester 2009 14 Or, the force on the first wire…..

15. Physics for Scientists and Engineers II, Summer Semester 2009 15 The Definition of 1 Ampere When the magnitude of the force per unit length between two long, parallel wires that carry identical currents and are separated by 1m is 2x10 -7 N/m, the current in each wire is defined to be 1 A.

16. Physics for Scientists and Engineers II, Summer Semester 2009 16 Ampere’s Law Top View

17. Physics for Scientists and Engineers II, Summer Semester 2009 17 Ampere’s Law Top View

18. Physics for Scientists and Engineers II, Summer Semester 2009 18 Ampere’s Law