GATE Physics: Questions 6 - 8 of 290

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Question number: 6

» Thermodynamics and Statistical Physics » Probability Ensembles

Appeared in Year: 2016

Short Answer Question▾

Write in Short

The entropy S of a system of N spins, which may align either in the upward or in the downward direction, is given by S=kBN[plnp+(1p)ln(1p)] . Here, kB is the Boltzmann constant. The probability of alignment in the upward direction is p . The value of p , at which the entropy is maximum is _. (Give your answer up to one decimal place)

Question number: 7

» Classical Mechanics » Conservation Laws

Appeared in Year: 2014

MCQ▾

Question

The recoil momentum of an atom is pA when it emits an infrared photon of wavelength 1500nm , and it is pB when it emits a photon of visible wavelength 500nm . The ratio pApB is –

Choices

Choice (4) Response
a.

1:1

b.

1:3

c.

1:3

d.

3:2

Question number: 8

» Thermodynamics and Statistical Physics » Macrostates and Microstates

Appeared in Year: 2015

MCQ▾

Question

Consider a system of N non – interacting spin 12 particles, each having a magnetic moment μ , is in a magnetic field B=Bz^ . If E is the total energy of the system, the number of accessible microstates Ω is given by,

Choices

Choice (4) Response
a.

Ω=(NEμB)!(N+EμB)!

b.

Ω=12(NEμB)!12(N+EμB)!

c.

Ω=N!12(NEμB)!12(N+EμB)!

d.

Ω=N!(N+EμB)!

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