Laws of Thermodynamics are a set of fundamental, experimentally validated principles that govern energy, heat, work, and entropy in physical systems. They are empirical laws derived from observation and are universally applied in physics and engineering.
The first law of thermodynamics, also called conservation of energy, expresses the principal of the conservation of energy. This means that the total amount of energy in the universe is constant and that it can neither be created or destroyed. This law states that for every gain in some type of energy will result in the loss in some other form.
The second law of thermodynamics, also called entropy, abbreviated as S, is a fundamental principle in physics and thermodynamics that describes the behavior of energy in a system. It can be stated in multiple ways, but one common formulation is, "The total entropy of an isolated system always tends to increase over time." Entropy can be thought of as a measure of the disorder or randomness in a system. The law implies that in any natural process, the overall level of disorder in the universe, as measured by entropy, will tend to increase or remain the same.
The third law of thermodynamics, also known as Nernst's theorem or the Nernst heat theorem, is about the ability to create an absolute zero temperature, where the entropy approaches a constant minimum value. It also states that it is not possible for any system to reach absolute zero. More specifically, the third law of thermodynamics states that the entropy of a pure, perfect crystal at absolute zero temperature is exactly equal to zero. In other words, as the temperature approaches absolute zero, the entropy of a perfect crystal approaches zero.
The zeroth law of thermodynamics is one of the fundamental principles in thermodynamics. When two thermal systems are in equilibrium and they with a third, then all are equal to each other, meaning \(A=B\) and \(B=C\) then \(A=C\). If a system does not transfer heat, it is in thermal equilibrium even though it can transfer heat. It establishes the concept of temperature and thermal equilibrium.
