34. one point, from Lecture 35, short explanations

(a) .4 Superconductivity. What two electromagnetic properties change as a superconductor goes through its critical temperature? (.2)
How might these two properties be useful to us? (.2)

(b) .4 Low T_c Superconductivity. What are a Cooper Pair (.1), an energy gap (.1), what do bosons have to do with them (.1), and how are these two quantum mechanisms related by the Bardeen/Cooper/Schrieffer theory (1972 Nobel) to the electrical conductivity (.1)?

(c) .2 High T_c Superconductivity. Give two features (.1 each) which are different about a high T_c superconductor from a low T_c superconductor.

37. one point, about a new subject but you can figure it out from earlier material in Unit 3, plus some material from Lectures 35 and 37, a group question, not easy but doable

The 1997 Nobel Prize. The 1997 Nobel Prize in Physics was awarded in October to Stephen Chu of Stanford University, Claude Cohen-Tannoudji of the École Normale Supérieure in Paris, and William Phillps ofthe National Institute of Standards and Technology in Gaithersburg, Maryland. The award (of about a million dollars) was for cooling atoms to 10s of millionths of a degree (Kelvin) above absolute zero and for trapping atoms with laser light.

(a) .4 Cooling. Use what you know about kinetic theory (.2), the dual nature of light(.1), and collisions (.1) to say how laser beams can cool atoms.

Revised November 30, 1997.