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Exercise 52 gives the Boltzmann distribution for the special case of simple harmonic oscillators, expressed in terms of the constant ε=±·³óÓ¬0/(2s+1). Exercise 53 gives the Bose-Einstein and Fermi-Dirac distributions in that case. Consider a temperature low enough that we might expect multiple particles to crowd into lower energy states:kBT=15ε. How many oscillators would be expected in a state of the lowest energy,E=0? Consider all three-classically distinguishable. boson, and fermion oscillators - and comment on the differences.

Short Answer

Expert verified

The number of oscillators expected if they were classically distinguishable be NBoltz(0)=5.

The number of oscillators expected if they were bosonNBE(0)=147 .

The number of oscillators expected if they were fermions NFD(0)=0.9933.

Step by step solution

01

Formula used

NBoltz(E)=EkBT1eF/hBT

NBE(E)=1e[KBT1−e−EJBT−1

NFD(E)=1eâ„ÄÓ¶ÄBTe1/Ï€BT−1+1

02

Given Information from question

kBT=15ξ

The Boltzmann distribution of equation (1) is checked first, using the energy condition of equation (5), along with Ebeing 0:

NBoltz(E)=EkBT1eEIIkBTNBoltz(0)=E15E1eÓ¬0v15ENBoltz(0)=5e0NBoltz(0)=5

So, the number of oscillators expected if they were classically distinguishable would beNBoltz(0)=5.

03

The Bose-Einstein distribution of equation is checked with the energy

The Bose-Einstein distribution of equation is checked with the energy condition of equation (5) along with E being 0:

NBE(E)=1eEZBT1−e−BEBT−1NBE(0)=1eӬjx15E1−E15E−1=1e01−e−5−1=111−e−5−1

That can be rearranged some to get rid. of the complex fraction:

NBE(0)=111−e−5−1−e−51−e−5=11−(1−e−5)1−e−5=1−e−5e−5

Solving further, we get

NBE(0)=1e−5e−5e−5=e−5−1=147

So, the number of oscillators expected if they were bosons would be NBE(0)=147.

04

The Fermi-Dirac distribution

From equation (3) the Fermi-Dirac distribution is,

NFD(E)=1e·¡Ï€BTeFKBT−1+1

NFD(0)=1ecov15EeFD15E+1=1e0e5+1=11e5+1=11e5+e5e5=11+e5e5=e51+e5

Therefore,

NFD(0)=e51+e5=148.4148.4+1=0.9933

So, the number of oscillators expected if they were fermionsNFD(0)=0.9933 .

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