Thermodynamics
NIOS · Class 12 · Physics
Complete topic list for Thermodynamics in NIOS Class 12 Physics. Key concepts, sub-topics, and what to focus on for board exams.
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See them allTopics in Thermodynamics
Basic Concepts: Heat, Temperature, and Thermodynamic Systems
- Heat is a form of energy that flows from a body at higher temperature to a body at lower temperature due to a temperature difference. It is NOT the same as internal energy.
- Temperature is the property that determines whether two bodies are in thermal equilibrium. Two bodies in thermal equilibrium have the same temperature.
- Unit of heat: 1 calorie = 4.18 Joules; 1 kcal = 1000 cal = 4180 J.
Thermodynamic Processes
- Isothermal Process: Temperature is constant (ΔT = 0). Occurs in perfectly conducting cylinders. ΔQ, ΔU, and ΔW are all finite. For an ideal gas, ΔU = 0, so ΔQ = ΔW.
- Adiabatic Process: No heat exchange (ΔQ = 0). Occurs in perfectly insulating cylinders. From First Law: ΔU = −ΔW. If gas is compressed, work is done ON the gas, ΔU increases (gas heats up). If gas exp
- Isobaric Process: Pressure is constant (ΔP = 0). Example: Heating water under atmospheric pressure. Work done W = PΔV is non-zero.
Zeroth Law of Thermodynamics and Triple Point
- Zeroth Law of Thermodynamics: If two bodies A and B are separately in thermal equilibrium with a third body C, then A and B are also in thermal equilibrium with each other.
- The Zeroth Law introduces the concept of TEMPERATURE as a fundamental property. It is the scientific basis for thermometers.
- Practical significance: A thermometer (body C) reads the same temperature when placed in contact with different bodies (A and B) that are in mutual thermal equilibrium.
Internal Energy and First Law of Thermodynamics
- Internal Energy (U) is the sum of kinetic energy (random molecular motion) and potential energy (intermolecular forces) of all molecules in the system.
- Internal energy is a STATE function — it depends only on the state (P, V, T) of the system, NOT on the path by which the state was reached.
- Internal energy can be increased by: (1) Adding heat to the system, or (2) Doing work ON the system.
Key Concepts
Central concept: Thermodynamics
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