Thermodynamics – JEE Mains Physics
1. Thermal Equilibrium and the Concept of Temperature
- Thermal equilibrium refers to the condition where two objects are at the same temperature and no heat flows between them.
- Temperature is the measure of the average kinetic energy of the particles in a system.
2. Zeroth Law of Thermodynamics
- The Zeroth Law states that if two systems are each in thermal equilibrium with a third system, they are in thermal equilibrium with each other.
3. Heat, Work, and Internal Energy
- Heat is the energy transferred due to a temperature difference.
- Work is the energy transferred when a force is applied to a system causing it to move.
- Internal Energy (U) is the total energy contained within a system, including both kinetic and potential energy of particles.
4. The First Law of Thermodynamics
- The First Law states that energy cannot be created or destroyed, only transformed from one form to another.
- Formula:
ΔU = Q - W
where ΔU is the change in internal energy, Q is the heat supplied, and W is the work done by the system.
5. Isothermal and Adiabatic Processes
- Isothermal Process: A process that occurs at a constant temperature. The change in internal energy is zero, and the heat supplied equals the work done by the system.
- Adiabatic Process: A process in which no heat is exchanged with the surroundings. The change in internal energy is equal to the work done.
6. The Second Law of Thermodynamics
- The Second Law states that the entropy of an isolated system always increases over time, and natural processes tend to move towards equilibrium.
7. Reversible and Irreversible Processes
- Reversible Process: A process that can be reversed without leaving any change in the system or surroundings.
- Irreversible Process: A process that cannot be reversed to return to the initial state without external changes.