CSIR Physical Sciences: Questions 290 - 293 of 401

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Question number: 290

» Thermodynamic and Statistical Physics » Blackbody Radiation

Appeared in Year: 2012

MCQ▾

Question

Consider black body radiation contained in a cavity whose walls are at temperature T. The radiation is in equilibrium with the walls of the cavity. If the temperature of the walls is increased to 2T and the radiation is allowed to come to equilibrium at the new temperature, the entropy of the radiation increases by a factor of (June)

Choices

Choice (4) Response

a.

8

b.

16

c.

4

d.

2

Question number: 291

» Electromagnetic Theory » Lorentz Invariance of Maxwell's Equation

Appeared in Year: 2012

MCQ▾

Question

Which of the following quantities is Lorentz invariant? (June)

Choices

Choice (4) Response

a.

E×B 2

b.

E 2 B 2

c.

E 2+ B 2

d.

E 2 B 2

Question number: 292

» Quantum Mechanics » Variational Method

Appeared in Year: 2012

MCQ▾

Question

What would be the ground state energy of the Hamiltonian – H=22md2dx2αδ(x) If variational principle is used to estimate it with the trial wavefunction ψ(x)=Aebx2 with b, as the variational parameter?

(Hint:x2ne2bx2dx=(2b)n12Γ(n+12)) (December)

Choices

Choice (4) Response

a.

α2mπ2

b.

mα2π2

c.

mα222

d.

2mα2π2

Question number: 293

» Quantum Mechanics » Elementary Theory of Scattering » Born Approximation

Appeared in Year: 2012

MCQ▾

Question

A free particle describe by a plane wave and moving in the positive z – direction undergoes scattering by a potential,

V(r)={0,if x a,if x >a

If V0 is changed to 2V0 , keeping R fixed, then the differential scattering cross- section, in the Born approximation, (June)

Choices

Choice (4) Response

a.

Increases to twice the original value

b.

Decreases to one fourth the original value

c.

Increases to four times the original value

d.

Decreases to half the original value

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