1. The graded exams will be returned next Tuesday, Nov 7
The graded exams will be returned next Tuesday, Nov 7. You will have until the next class on Thursday, Oct 6 to rework the problems you got wrong and receive 50% added credit. Make sure you are in class as you will no have another opportunity to rework the exam. I will be going over the answers in class on Thursday. This will also be your only opportunity to ask for corrections/clarifications on any grading mistakes.
The homework assignment will be on line this afternoon but will not be due until Tuesday, Nov 14. This will give you the opportunity to start work on the problems so that you will not be overloaded with homework and the exam rework next week.

2. Forces and Torques on the Current Loop
Net force is zero

3. The Torque is not zero

4. Magnetic Dipole Moment
Loops and Coils
For solenoid

5. Example: Force and Torque on a Circular Current Loop

6. Example: Force on a Current Loop in Non-Uniform Field
(2)
(1)
(3)
(4)

7. Magnetic Dipole in a Non-uniform Magnetic Fieldy

8. Magnetic Dipoles and How Magnets Work

9. The Direct-Current Motor

10. Magnetic Field of a Moving Charge
Magnetic field of a point charge
moving with constant velocity

11. Example: Force between two moving protons
Find the ratio of electric and magnetic forces on the protons
Magnetic field of the lower proton at
the position of the top one

12. Magnetic Field of Current Element
The Biot-Savart law.

13. Magnetic field around a straight wire

14. Magnetic Field of Two Wires
Field at points on the x-axis
to the right of point (3)
Magnetic field outside of a conductor pair falls off more rapidly

15. Magnetic field of a circular arc

16. Falls off just as the electric field of the electric dipole
Magnetic Field of a Circular Current Loop
Falls off just as the electric field of the electric dipole
Magnetic Field on the Axis of a Coil

17. The magnetic field of a (small) loop behaves “on the outside” like the electric field of the electric dipole of the same orientation – that’s why “magnetic dipole”.

18. Magnetic force between two parallel conductors with currents

19. Example: Two straight, parallel, superconducting wires 4
Example: Two straight, parallel, superconducting wires 4.5 mm apart carry 15,000 A current each in opposite directions
Should we carry about the mechanical strength of the wires?