Balance Condition and Temperature

Storyboard

To model systems using statistical mechanics, we need to investigate how statistical ensembles can be influenced by the parameters that describe the macroscopic system. For particles, temperature is established as a parameter that reflects whether systems are in equilibrium, maintaining their energies at a constant level.

>Model

ID:(436, 0)



A System in contact with a reservoir

Image

We can study what happens when we put two systems of particles in contact in such a way that they can exchange energy but not particles.

Let's also assume that the system is isolated from the surroundings, meaning it has a total energy of $E_0$.

Suppose initially the first system has an energy of $E$, which is associated with $\Omega(E)$ states.

Since the total energy is $E_0$, the second system can only have the energy $E_0-E" and a number of associated states $\Omega(E_0-E)$.

Once we bring them into contact, they can exchange energy until they reach some equilibrium. In this regard, the value of $E$ will vary, and the probability of finding the systems such that the first one has a value of $E$ will also vary.

ID:(11541, 0)



Comparing the number of state curves

Image

When we compare how the number of states varies with energy $E$, we observe that the behavior of the system and the reservoir is opposite:

This happens because as the energy increases, the energy of the reservoir decreases, leading to a reduction in the number of states it can access.

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Forming a maximum

Image

When we multiply the number of cases, we obtain a function with a very pronounced peak.

The system is more likely to be found at the energy where the peak of the probability curve occurs.

ID:(11543, 0)



Balance Condition and Temperature

Model

To model systems using statistical mechanics, we need to investigate how statistical ensembles can be influenced by the parameters that describe the macroscopic system. For particles, temperature is established as a parameter that reflects whether systems are in equilibrium, maintaining their energies at a constant level.

Variables

Symbol
Text
Variable
Value
Units
Calculate
MKS Value
MKS Units
$\beta$
beta
Beta del reservorio
1/J
$\beta$
beta
Beta del sistema
1/J
$k_B$
k_B
Constante de Boltzmann
J/K
$E_2$
E_2
Energía del reservorio
J
$E$
E
Energía del sistema
J
$C$
C
Factor de normalización
-
$\Omega_E$
Omega_E
Numero de estados del reservorio con energía $E'$
-
$\Omega(E_0-E)$
Omega_E_0E
Numero de estados del reservorio con energía $E_0-E$
-
$\Omega_E$
Omega_E
Numero de estados del sistema con la energía $E$
-
$P_E$
P_E
Probabilidad del sistema de tener una energía $E$
-
$T_2$
T_2
Temperatura del reservorio
K
$T$
T
Temperatura del sistema
K

Calculations


First, select the equation:   to ,  then, select the variable:   to 

Symbol
Equation
Solved
Translated

Calculations

Symbol
Equation
Solved
Translated

 Variable   Given   Calculate   Target :   Equation   To be used



Equations


Examples

We can study what happens when we put two systems of particles in contact in such a way that they can exchange energy but not particles.

Let's also assume that the system is isolated from the surroundings, meaning it has a total energy of $E_0$.

Suppose initially the first system has an energy of $E$, which is associated with $\Omega(E)$ states.

Since the total energy is $E_0$, the second system can only have the energy $E_0-E" and a number of associated states $\Omega(E_0-E)$.

Once we bring them into contact, they can exchange energy until they reach some equilibrium. In this regard, the value of $E$ will vary, and the probability of finding the systems such that the first one has a value of $E$ will also vary.

(ID 11541)

When we compare how the number of states varies with energy $E$, we observe that the behavior of the system and the reservoir is opposite:

This happens because as the energy increases, the energy of the reservoir decreases, leading to a reduction in the number of states it can access.

(ID 11542)

When we multiply the number of cases, we obtain a function with a very pronounced peak.

The system is more likely to be found at the energy where the peak of the probability curve occurs.

(ID 11543)


ID:(436, 0)