Thermal concepts

Basic Concepts of Thermal Physics

Thermal physics is the branch of physics that deals with the effects of heat and temperature on physical systems.
Temperature is a measure of the average kinetic energy of the particles in a material. It’s expressed in units of degrees Celsius (°C), kelvin (K), or degrees Fahrenheit (°F).
The zeroth law of thermodynamics states that if two systems are each in thermal equilibrium with a third, then they are in thermal equilibrium with each other. This law allows us to make measurements of temperature.

Heat Transfer

Conduction is the process by which heat is directly transmitted through a substance when there is a difference in temperature between adjoining regions, without movement of the material
Convection involves the movement of warmer particles to cooler areas within a fluid (could be a liquid or a gas)
Radiation involves the transfer of heat energy in the form of electromagnetic waves.

Thermal Expansion

Most materials expand when they’re heated, and this is known as thermal expansion.
Generally, the amount of expansion is directly proportional to the temperature change.

Specific Heat Capacity and Latent Heat

The specific heat capacity of a substance is the amount of heat energy required to raise the temperature of 1 kg of the substance by 1 °C.
The latent heat of a substance is the heat energy required to change the state of 1 kg of a substance without changing its temperature.

First Law of Thermodynamics

The first law of thermodynamics (or the law of energy conservation) states that energy can neither be created nor destroyed, only converted from one form to another.
In any process, the total energy of a closed system is always conserved.

Second Law of Thermodynamics

The second law of thermodynamics states that the total entropy (disorder) in an isolated system will always increase over time, or remain constant in ideal cases where the system is in a steady state or undergoing a reversible process.
In practical terms, this means energy always flows from areas of high temperature to areas of low temperature.