All Laws Of Thermodynamics | Four Laws Of Thermodynamics

 Four Laws Of Thermodynamics

The Laws of Thermodynamics:

The laws of thermodynamics are fundamental principles that interrelate heat, energy, and work. The laws of thermodynamics are the primary part of the explanation of why energy is transferred from one form to another but persists in its totality. For this reason alone, they are applied in nearly all domains, from physics and engineering through chemistry and even biology.

There are four laws which define energy in a system in terms of the flow and transformation of it. These laws apply to systems that can be as small as a gas particle or as large as the universe. The four laws are:

Zeroth Law of Thermodynamics-Thermal Equilibrium:

The zeroth law of thermodynamics is a declaration of temperature definition. It simply states that if two systems, A and B are each in thermal equilibrium with the third system, C then A and B must also be in thermal equilibrium with each other. This principle allows for temperature as a measurable property of matter.

Equation for Zeroth Law:

                     If TA=TC, and TB=TC, then TA=TB

This law is pertinent to developing thermometers and to understand that heat moves from hot objects to cold ones and continues till both bodies are in equilibrium.

First Law of Thermodynamics (Conservation of Energy):

The law of energy conservation, or in other words, the first law of thermodynamics explains that energy cannot be created nor destroyed. It can, however be transferred or converted from one form to another. 

In a closed system, the total internal change (ΔU) equals the heat added to the system (Q) minus the work done by the system (W).

Expression for the First Law of Thermodynamics:

                                              ΔU=Q−W

Where:

ΔU is the change in internal energy.

Q is the heat added to the system.

W is the work done by the system.

This law is basic when explaining energy balance. For example, in an internal combustion engine, chemical energy in the fuel is changed into heat, some of which is converted into work (actual movement of the car), while some is wasted as heat.

Applications:

Internal Combustion Engine: Energy coming from fuel is converted into work by an internal combustion engine.

Heating Systems: In a simple household heating system, the energy is conserved as the heat flows from heater to warm up the room.

Second Law of Thermodynamics (Entropy and Irreversibility):

The second law of thermodynamics is introducing the term entropy (S) or an expression for the disorganized or random nature of a system. According to the law, total entropy of a system and its surroundings always increases in any form of energy transfer or transformation. This means natural processes are not reversible; they tend toward states of maximum entropy.

Equation of the Second Law of Thermodynamics:

                                                    ΔS≥0

Where:

ΔS Change in entropy.

It explains why certain processes, like the transfer of heat from hot to cold objects, are impossible to reverse. It also gives the bottom line limit on the efficiency of heat engines.

Carnot Efficiency-is a straight application of the second law-sets the maximum efficiency a heat engine can have:

η=1 − TC\TH

In these expressions:

η is the efficiency.

TC is the temperature of the cold reservoir.

TH is the temperature of the hot reservoir.

Applications:

Heat Engines: Based on the second law, the efficiency of heat engines such as steam turbines and car engines cannot exceed the limit defined by the said law. In turn, waste heat will be produced, and loss of some energy will always happen.

Refrigerators: Refrigerators make use of work to revert the natural entropy of the flow from the cold to the hot side.

Biological Systems: Living organisms increase the entropy of the surroundings due to the internal order maintained by the organism itself.

Third Law of Thermodynamics (Entropy at Absolute Zero and Zero):

The third law of thermodynamics states that when a system is brought near absolute zero temperature, or -273.15°C, the entropy of a system approaches some minimum or constant value. At absolute zero for a perfect crystal, the entropy would be zero since there is only one possible microstate in such a case.

Equation for Third Law of Thermodynamics:

                             S→0        as         T→0

Where:

S is the entropy.

The temperature is T.

While the third law cannot be exactly achieved, it gives a conceptual way of how materials could behave at very low temperatures by advancing cryogenics and quantum computing.

Applications:

Cryogenics: This third law is crucial for the understanding and explanation of the behavior of gases and solids at very small temperature values, influencing every research on superconductors and quantum computers.

Physics of Very Low Temperature: Investigation of entropy bounds near the absolute zero, both associated with material sciences and development of ultra-efficient systems

Conclusion:

The laws of thermodynamics provide basic explanations of energy transfer, conservation, and change in any system. These laws range from the zeroth law, which actually speaks to defining temperature and thermal equilibrium, through to the third law, which sets limits at absolute zero. Everything is comprehended under these laws: natural processes, as well as technological advancements. With a solid understanding of these laws, we can design better systems, gain an appreciation for the universe, and move into areas such as engineering and physics, all the way up to quantum mechanics.

These laws not only influence the physical world but also guide innovations in energy systems, engines, and refrigeration, ensuring we improve the efficiency and sustainability of life events day by day.