# Chapter 9 : Statistical Thermodynamics¶

## Example 9.1 Page No : 542¶

In [1]:
# Input data
N = 6000.  # Number of particles in a system
e = 3.  # The number of energy states with equal spacing
n1 = 3000.  # Number of particles in the lower level
n2 = 2500.  # Number of particles in the middle level
n3 = 500.  # Number of particles in the upper level
n11 = 3001.  # Number of particles in the lower level in the second case
n22 = 2498.  # Number of particles in the middle level in the second case
n33 = 501.  # Number of particles in the upper level in the second case
g = 1.  # Let us assume the probability of locating a particle in a certain energy state is one

# Calculations
P1 = 1. / (2500. * 2499)  # The probability in the first case
P2 = 1. / (3001. * 501)  # The probability in the second case
P = P2 / P1  # Comparing the relative probabilities

# Output
print 'By comparing the relative probabilities P = %3.1f  \n (It means the transfer of one particle from the middle to the\n upper and the lower state has changed the probability by a factor %3.1f \n Hence both the distributions are not near the equilibrium state)' % (P, P)

By comparing the relative probabilities P = 4.2
(It means the transfer of one particle from the middle to the
upper and the lower state has changed the probability by a factor 4.2
Hence both the distributions are not near the equilibrium state)