 Law of Thermodynamics: Definition, Types and Example - Electrical Diary -->

# What is the law of thermodynamics?

The law of thermodynamics is a set of fundamental principles that describe the relationship between heat, energy, and work in physical systems. There are four laws of thermodynamics, which are as follows:
• The First Law of Thermodynamics
• The Second Law of Thermodynamics
• The Third Law of Thermodynamics:
• The Zeroth Law of Thermodynamics

## What is the First Law of Thermodynamics?

The First Law of Thermodynamics, also known as the Law of Conservation of Energy, states that energy cannot be created or destroyed, only transformed from one form to another. This means that the total energy in a system remains constant, although it may be redistributed.

For example, consider a simple heat engine, such as a steam engine. The steam engine converts heat energy from a hot source, such as a boiling pot of water, into mechanical energy, which can be used to do work, such as driving a piston. According to the First Law of Thermodynamics, the total amount of energy in the system remains constant. This means that the energy lost by the hot source in the form of heat must be equal to the energy gained by the piston in the form of mechanical energy.

Another example is a car engine. When gasoline is burned in the engine, it releases heat energy, which is used to power the car. According to the First Law of Thermodynamics, the total energy in the system remains constant. This means that the energy released by the gasoline in the form of heat must be equal to the energy gained by the car in the form of motion.

In both of these examples, the energy is transformed from one form to another, but the total amount of energy in the system remains constant. The First Law of Thermodynamics provides a fundamental understanding of energy conservation and is a key principle in many branches of science and engineering, including physics, mechanical engineering, and chemical engineering.

### What is The Second Law of Thermodynamics?

The Second Law of Thermodynamics states that the total entropy, or disorder, of a closed system, will always increase over time. This means that it is impossible for a process to occur in a closed system which results in a decrease in the total entropy of the system.

Entropy can only be decreased by transferring heat from a hotter body to a colder one, but this transfer must always result in an overall increase in entropy. The entropy increase is a measure of the amount of energy that is unavailable for use and is dispersed as waste heat.

For example, consider a hot cup of coffee that is left on a table to cool. Over time, the heat energy from the coffee will be transferred to the surrounding air, causing the temperature of the coffee to decrease and the temperature of the air to increase. According to the Second Law of Thermodynamics, the total entropy of the system, which includes the coffee and the air, will increase over time.

Another example is a car engine. When gasoline is burned in the engine, it releases heat energy, which is used to power the car. However, some of the energy is lost as waste heat, which cannot be used to do work. According to the Second Law of Thermodynamics, the total entropy of the system, which includes the engine and the surrounding air, will increase over time.

The Second Law of Thermodynamics provides a fundamental understanding of the nature of energy and its relationship to entropy and is a key principle in many branches of science and engineering, including thermodynamics, mechanical engineering, and chemical engineering. It is also a central concept in the study of energy efficiency and sustainability, as it highlights the importance of minimizing energy waste and maximizing energy efficiency.

### What is The Third Law of Thermodynamics?

The Third Law of Thermodynamics states that as the temperature of a system approaches absolute zero, the entropy of the system approaches a minimum value. This means that it is impossible to reach absolute zero in a finite number of steps, as the entropy would approach, but never reach zero.

Absolute zero is the temperature at which the thermal motion of all particles in a system comes to a complete stop. At this temperature, the entropy of the system would be zero, if it were possible to reach it. However, the Third Law of Thermodynamics states that it is not possible to reach absolute zero in a finite number of steps.

The Third Law of Thermodynamics provides a fundamental understanding of the relationship between entropy and temperature and is a key principle in many branches of science and engineering, including thermodynamics, mechanical engineering, and chemical engineering. It also has important implications for the study of materials and the development of new materials with specific properties, as it provides a basis for understanding the behavior of materials at extremely low temperatures.

### What is The Zeroth Law of Thermodynamics?

The Zeroth Law of Thermodynamics states that if two systems are each in thermal equilibrium with a third system, then they are in thermal equilibrium with each other. This law provides a basis for the definition of temperature and the measurement of temperature differences between two systems.

For example, consider a hot cup of coffee and a cold glass of iced water. If the coffee and the ice water are each in thermal equilibrium with a room-temperature object, such as a metal spoon, then they are also in thermal equilibrium with each other. This means that the temperature of the coffee is the same as the temperature of the ice water, and a thermometer placed in either the coffee or the ice water would show the same temperature.

The Zeroth Law of Thermodynamics is the starting point for the study of thermodynamics and provides a fundamental understanding of the nature of temperature and thermal equilibrium. It is a key principle in many branches of science and engineering, including thermodynamics, mechanical engineering, and chemical engineering. It also has important implications for the study of energy transfer and the measurement of temperature in a variety of systems and processes.