Dear PHYS 3220 students,

today’s class is cancelled after the tragic event of last night. Here is the make-up plan, for which I need your collaboration. Basically, most material in today’s sections 11.1-11.6 has already been covered in class. I will cover the remaining parts this coming Friday, together with the regularly scheduled sections 11.7-11.12. Your contribution comes in reading sections 11.1-11.6 _before_ coming to class this Friday. The rest of this email contains more details.

- Today’s class would have covered sections 11.1-11.6 of the textbook, which comprise the first part of the chapter on magnetic fields in matter. As for the analogous chapter on electric fields in matter, use chapter 11 to verify that you understand what we learned about magnetic fields. We have actually already covered large parts of today’s sections in class already: the absence of magnetic charge (divergence of B equal to zero), the equivalence of a current loop to a magnetic dipole (and the magnetic dipole moment), the force on magnetic dipoles in magnetic fields (the potential energy is minus magnetic moment dot magnetic field, and the torque is magnetic moment cross magnetic field). We have not covered the relation between magnetic moment and angular momentum (section 11.5 and first three paragraphs of 11.6), nor how substances respond to magnetic fields (section 11.1, where the concepts of diamagnetic, paramagnetic and ferromagnetic substances are introduced).

- I expect you have already prepared the class-to-class homework due today (CTC18). For logistical reasons, you can turn it at the beginning of class this Friday November 3.

- Between now and Friday, read sections 11.1-11.6 in the textbook. I suggest you write the reading part of CTC19 while you read those sections. You may also work out other parts of CTC19 between now and Friday, if you wish.

- CTC19 is now due Tuesday next week (November 7), _together with CTC20_. So two class-to-class homework assignments are due next Tuesday, but as I said I expect you have already done CTC18 by today, and you can start working on CTC19 this week.

See you in class Friday,

Paolo Gondolo