The energy per oscillator of an isolated system of a large number of i...
Given Information:
- The energy per oscillator of an isolated system of a large number of identical non-interacting fermions in a one-dimensional harmonic oscillator potential is given by 5hω/4, where ω is the angular frequency of the harmonic oscillator.
- We need to determine the entropy of the system per oscillator.
Explanation:
1. Energy per Oscillator:
The energy per oscillator is given by the formula 5hω/4.
2. Fermions and the Pauli Exclusion Principle:
- Fermions are a type of fundamental particles that follow the Pauli Exclusion Principle.
- According to the Pauli Exclusion Principle, no two identical fermions can occupy the same quantum state simultaneously.
- In a one-dimensional harmonic oscillator potential, each energy level can accommodate two fermions (one with spin up and one with spin down) due to the two available spin states.
- Therefore, the energy per oscillator for fermions should be twice the energy per oscillator for a single particle.
3. Deriving the Energy per Oscillator for a Single Particle:
- Let's assume the energy per oscillator for a single particle in a one-dimensional harmonic oscillator potential is E.
- According to the given information, the energy per oscillator for fermions is 5hω/4.
- Since this energy is for two fermions, we can write: 5hω/4 = 2E
- Solving for E: E = 5hω/8
4. Entropy per Oscillator:
- The entropy of the system per oscillator can be calculated using the formula: S = k ln(Ω), where k is Boltzmann's constant and Ω is the number of microstates.
- In this case, each energy level can accommodate two fermions, and the number of microstates can be calculated using combinatorics.
- The total number of microstates is given by Ω = (2N)! / [(N!)^2], where N is the total number of fermions.
- For a large number of fermions, we can use Stirling's approximation to simplify the calculation.
- By substituting the value of N = 2 into the formula, we can calculate the entropy per oscillator.
5. Calculation:
- Substituting N = 2 into the formula: Ω = (2(2))! / [((2)!)^2] = 4! / [(2!)^2] = 24 / 4 = 6
- Using S = k ln(Ω), the entropy per oscillator is: S = k ln(6)
- To find the value of k, we need to know the units of the given energy per oscillator (5hω/4).
- Assuming the energy is in joules, we can use the value of Boltzmann's constant k = 1.38 x 10^-23 J/K.
- Calculating the entropy: S = (1.38 x 10^-23 J/K) ln(6) ≈ 0.56
Answer:
- The entropy of the system per oscillator is approximately 0.56 (option b).
The energy per oscillator of an isolated system of a large number of i...
Introduction:
We are given that we have an isolated system of a large number of identical non-interacting fermions in a one-dimensional harmonic oscillator potential. We need to determine the entropy of the system per oscillator.
Explanation:
To find the entropy per oscillator, we can use the formula for the entropy of a fermionic system:
S = k * ln(W)
Where S is the entropy, k is the Boltzmann constant, and W is the number of microstates of the system.
Step 1: Finding the number of microstates (W):
In the given system, each fermion can occupy one of the energy levels of the one-dimensional harmonic oscillator potential.
The energy levels of the one-dimensional harmonic oscillator are given by:
E_n = (n + 1/2) * h * omega
Where E_n is the energy level, n is a non-negative integer, h is the Planck constant, and omega is the angular frequency of the harmonic oscillator.
The energy per oscillator is given as 5h * omega / 4.
We can equate this to the energy levels and solve for n:
5h * omega / 4 = (n + 1/2) * h * omega
Simplifying the equation, we get:
5/4 = n + 1/2
n = 3/4
Therefore, there are 4 energy levels with n = 0, 1, 2, and 3.
Thus, the number of microstates (W) is equal to the number of ways we can distribute the fermions among the 4 energy levels. This can be calculated using the concept of combinations:
W = (n + r - 1) choose (r)
Where n is the number of energy levels and r is the number of fermions.
In this case, since each fermion can occupy one energy level, r is also equal to 4.
Calculating the combinations, we get:
W = (3 + 4 - 1) choose (4)
= 6 choose 4
= 15
Step 2: Calculating the entropy:
Now that we have the number of microstates (W), we can calculate the entropy (S) using the formula:
S = k * ln(W)
Assuming k = 1 for simplicity, we have:
S = ln(15)
≈ 2.71
Conclusion:
The entropy of the system per oscillator is approximately ln(15) or 2.71.
Therefore, the correct option is (c) 0.63.