Homework Question about Statistical Mechanics

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Homework Help Overview

The discussion revolves around a statistical mechanics problem involving two identical Einstein solids in thermal contact, focusing on the calculation of macro-states and micro-states, as well as entropy expressions under different conditions.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the relevant quantities and the importance of correctly identifying the total energy in terms of energy quanta. Questions are raised about the distribution of energy quanta among oscillators and the implications for calculating microstates. There is also exploration of the general expression for microstates and confusion regarding the variable q and its relation to the total energy.

Discussion Status

The discussion is active, with participants attempting to clarify concepts and definitions. Some guidance has been provided regarding the initial steps to take, but there remains uncertainty about specific variables and their meanings. Multiple interpretations of the energy distribution are being explored.

Contextual Notes

Participants are grappling with the definitions of energy quanta and the implications of using different values for q in their calculations. There is also a mention of the need to apply the Stirling approximation for entropy calculations.

Elizabeth Chick
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Homework Statement



Consider the system of two large, identical Einstein solids, each with oscillators, in thermal contact with each other. Suppose the total energy of the system is 2 units of the energy quanta, i.e., =2ℏ, (i) how many MACRO-states (e.g., one macro-state corresponds to one where all the energy =2ℏ is taken by the first solid, and another corresponds to the case where half of the is taken by the first solid and another half by the second. The latter is the most likely state); (ii) Find a general (approximate) expression for the total number of MICRO-states Ω for the combined system, (iii) An expression for Ω=Ωmax when the system is in its most likely macro-state. (iv) Express the entropy of the combined system when (a) all of the micro-states are allowed, and (b) when the system is in its most likely macro-state, using the Sterling approximation: ln!=ln−.

Full Question as below
https://ibb.co/eZrrTx

Homework Equations

The Attempt at a Solution

 
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Start by writing down all relevant quantities: One solid has N1 oscillators, etc. Total energy must ne 2ħω, not just 2ħ (units!) where ω is the frequency of the oscillators. Ask yourself questions. If you distribute 2 quanta in N1 oscillators, how many microstates is that? That should start you off.
 
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Chandra Prayaga said:
Start by writing down all relevant quantities: One solid has N1 oscillators, etc. Total energy must ne 2ħω, not just 2ħ (units!) where ω is the frequency of the oscillators. Ask yourself questions. If you distribute 2 quanta in N1 oscillators, how many microstates is that? That should start you off.
Got it, thanks so much!
 
Last edited by a moderator:
Chandra Prayaga said:
Start by writing down all relevant quantities: One solid has N1 oscillators, etc. Total energy must ne 2ħω, not just 2ħ (units!) where ω is the frequency of the oscillators. Ask yourself questions. If you distribute 2 quanta in N1 oscillators, how many microstates is that? That should start you off.

I am trying to work on question (ii), the general expression of approximation of one solid would be Ω = (q+N/q)^q⋅(q+N/N)^N, and the total Ω = Ω1⋅Ω2 now there are two solids in the system with a total energy of 2N units, what should be the q? If I substitute 2N into q, it means that each solid has 2N units of energy?
 
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I am confused. What is q? And, are you distributing 2 quanta of energy, or 2N quana of energy?
 

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