Thermodynamic and Statistical Physics (CSIR Physical Sciences): Questions 53  55 of 56
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Question number: 53
» Thermodynamic and Statistical Physics » Ising Model
Appeared in Year: 2011
Question
A one – dimensional chain consists of a set of N rods each of length . When stretched by a load, each rod can align either parallel or perpendicular to the length of the chain. The energy of a rod is when aligned parallel to the length of the chain and is when perpendicular to it. When the chain is in thermal equilibrium at temperature T, its average length is – (December)
Choices
Choice (4)  Response  

a. 


b. 


c. 


d. 


Question number: 54
» Thermodynamic and Statistical Physics » BoseEinstein Condensation
Appeared in Year: 2011
Question
The excitations of a three – dimensional solid are bosonic in nature with their frequency and wave – number k are related by in the large wavelength limit. If the chemical potential is zero, the behaviour of the specific heat of the system at low temperature is temperature is proportional to – (December)
Choices
Choice (4)  Response  

a. 


b. 


c.  T 

d. 


Question number: 55
» Thermodynamic and Statistical Physics » Thermodynamic Potentials
Appeared in Year: 2011
Question
A heater and a thermocouple are used to measure and control temperature T of a sample at . A feedback circuit supplies power ‘P’ to the heater according to the equation with approximately tuned values of coefficients G and D. In order to maintain temperature stability in the presence of an external heat perturbation which causes small but rapid fluctuation of temperature, it is necessary to, (December)
Choices
Choice (4)  Response  

a.  Decrease G 

b.  Increase G 

c.  Increases D 

d.  Decrease D 
