• QUESTIONS BEFORE LECTURE 35

now think about these

• What is meant by absolute zero?
• How do you cool gases? liquids? solids?
• What is meant by phase transition?
• What is meant by critical temperature?
• What unit is spin quantized in?
• What does fermion refer to?
• What does boson refer to?
• How many fermions can be in the ground state?
• How many bosons can be in the ground state?
• What do we mean by spin up or down?
• What is the Fermi energy?
• What temperature is characteristic of a low T_c superconductor?
• What two electromagnetic properties change at the critical temperature for a superconductor?
• What two quantum mechanisms explain these changes, according to the BCS theory?
• How might we commercially exploit these two changes?
• What is a Cooper Pair?
• Why is there an energy gap in the BCS theory?
• What temperature is characteristic of a high T_c superconductor?
• What do we know about the mechanism for superconductivity for high T_c?