Thermodynamic and Statistical Physics (CSIR Physical Sciences): Questions 44 - 46 of 56

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Question number: 44

» Thermodynamic and Statistical Physics » Free Energy

Appeared in Year: 2012

MCQ▾

Question

The free energy difference between the superconducting and the normal states of a material is given by, ΔF=FSFN=α ψ 2+β2 ψ 4 where ψ is an order parameter and α and β are constants such that α>0 in the normal and α<0 in the superconducting state, while β>0 always. The minimum value of ΔF is – (December)

Choices

Choice (4) Response

a.

3α22β

b.

α22β

c.

5α22β

d.

α2β

Question number: 45

» Thermodynamic and Statistical Physics » Free Energy

Appeared in Year: 2011

MCQ▾

Question

Gas molecules of mass ‘m’ are confined in a cylinder of radius R and height L (With R > > L) kept vertically in the Earth’s gravitational field. The average energy of the gas at low temperature (such that mgLkBT ) is given by, (December)

Choices

Choice (4) Response

a.

2NkBT

b.

NkBT2

c.

3NkBT2

d.

5NkBT2

Question number: 46

» Thermodynamic and Statistical Physics » Classical and Quantum Statistics

Appeared in Year: 2011

MCQ▾

Question

Consider a system of N non – interacting spins, each of which has classical magnetic moment of magnitude μ . The Hamiltonian of this system in an external magnetic field H is H=i=1NμiH

where μi is the magnetic moment of the ith spin. The magnetization per spin at temperature T is: (June)

Choices

Choice (4) Response

a.

μ[coth(μHkBT)kBTμH]

b.

μtanh(μHkBT)

c.

μ2HkBT

d.

μ[sinh(μHkBT)]

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