Points to Remember: Thermal Physics - Key Concepts & Definitions for Science Students
Points to Remember - Thermal Physics | Science
Fundamental Concepts
- The SI unit of heat energy absorbed or evolved is joule (J)
- Heat always flows from a system at higher temperature to a system at lower temperature.
- Temperature is defined as the degree of hotness of a body. The SI unit of temperature is kelvin (K).
- All the substances will undergo one or more of the following changes when heated:
- Temperature of the substance rises.
- The substance may change state from solid to liquid or gas.
- The substance will expand when heated.
- All forms of matter (solid, liquid and gas) undergo expansion on heating.
- For a given rise in temperature, a liquid will have more expansion than a solid and a gaseous substance has the highest expansion than the other two.
- If a liquid is heated directly without using any container, then the expansion that you observe is termed as real expansion of the liquid.
- The expansion of a liquid apparently observed without considering the expansion of the container is called the apparent expansion of liquid.
- For a given heat energy, the real expansion is always more than that of apparent expansion.
- If the atoms or molecules of a gas do not interact with each other, then the gas is said to be an ideal gas or a perfect gas.
- Ideal gas equation, also called as equation of state is \(PV = RT\). Here, R is known as universal gas constant whose value is 8.31 J mol-1K-1