Thermodynamic and Statistical Physics (CSIR (Council of Scientific & Industrial Research) Physical Sciences): Questions 47 - 49 of 56

Assume that the free energy of a magnetic system has an expansion in the order parameter M of the form , with . As the temperature is lowered below , the system undergoes a phase transition. The behaviour of the order parameter just below the transition, where is very small, is best described by – (December)

Consider an ideal Bose gas in three dimensions with the energy – momentum relation with . The range of for which this system may undergo a Bose – Einstein condensation at a non- zero temperature is – (June)

A gas of N non- interacting particles is in thermal equilibrium at temperature T. Each particle can be in any of the possible non – degenerate state of energy . The average energy per particle of the gas, when , is – (December)