Thermodynamic and Statistical Physics (CSIR Physical Sciences): Questions 50 - 52 of 56

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Question number: 50

» Thermodynamic and Statistical Physics » Maxwell Relations

Appeared in Year: 2012

MCQ▾

Question

The energy required to create a lattice vacancy in a crystal is equal to 1eV . The ratio of the number densities of vacancies n1200Kn300K , when crystal is equilibrium at 1200 K and 300 K, respectively, is approximately, (June)

Choices

Choice (4) Response
a.

exp(15)

b.

exp(30)

c.

exp(15)

d.

exp(30)

Question number: 51

» Thermodynamic and Statistical Physics » Fermi Gases

Appeared in Year: 2011

MCQ▾

Question

The energy levels of electrons of mass ‘m’ and charge ‘e’ confined in an area A in the xy – plane with a uniform magnetic field B applied in the z – direction are given by En=(n+12)eBmc,n=0, 1,2, the degeneracy of each level is eBAc . The lowest level is completely filled and the others are empty. The Fermi energy 2N2πmA , where, N is the total number of electrons, is – (December)

Choices

Choice (4) Response
a.

Coincident with the n=0 level

b.

Midway between the n=0 and the n=1 levels

c.

Midway between the n=1 and the n=2 levels

d.

Coincident with the n=1 level

Question number: 52

» Thermodynamic and Statistical Physics » Diffusion Equation

Appeared in Year: 2011

MCQ▾

Question

Consider two independently diffusing non-interacting in 3 – dimensional space, both placed at the origin at time t=0 . These particles have different diffusion constants D1 and D2 . The quantity [R1(t)R2(t)]2 where R1(t) and R2(t) are the positions of the particles at time t , behaves as – (June)

Choices

Choice (4) Response
a.

6tD1D2

b.

6tD12+D22

c.

6t(D1+D2)

d.

6t(D1D2)

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