Introduction to Thermodynamics

Thermodynamics is a key chapter in NEET Physics that studies the relationship between heat, work, and energy in a system. Understanding thermodynamics is crucial for solving questions on energy transfer, internal energy, and thermodynamic processes.

StudentBro notes provide structured, NEET-focused explanations along with derivations and solved examples to make preparation easier.

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System, Surroundings, and Thermodynamic State

• System: Part of the universe under study (e.g., gas in a cylinder)

• Surroundings: Everything outside the system

• Boundary: Separates system and surroundings

• State of a system: Defined by properties like pressure, volume, temperature, and internal energy

• NEET often tests conceptual understanding of system types: open, closed, and isolated.

Work Done by a System

• Definition: Work done by the system is the energy transferred when a force is applied through a distance.

• Formula: W = ∫ P dV

• Positive if work is done by the system, negative if done on the system

• NEET numerical problems often include work done in expansion or compression of gases.

Heat Transfer

• Definition: Energy transferred between system and surroundings due to temperature difference

• Modes: Conduction, Convection, Radiation

• Positive if heat is absorbed by the system, negative if released

• NEET questions may involve calculating heat absorbed or released during thermodynamic processes.

Internal Energy (U)

• Definition: Total energy associated with the microscopic motion of particles in the system

• Depends on temperature and state of the system

• Change in internal energy: ΔU = Q − W for reversible processes

• NEET numericals often involve internal energy change in isothermal, adiabatic, or isobaric processes.

First Law of Thermodynamics

• Statement: Energy of a system is conserved; heat added = increase in internal energy + work done by the system

• Formula: ΔU = Q − W

• Special cases:

  • Isothermal process (ΔU = 0): Q = W

  • Adiabatic process (Q = 0): ΔU = −W

  • Isochoric process (W = 0): ΔU = Q

  • Isobaric process (constant P): Q = ΔU + PΔV

NEET questions test both conceptual understanding and numerical calculations using these formulas.

Thermodynamic Processes

1. Isothermal Process: Temperature constant, internal energy does not change, work done equals heat absorbed.

2. Adiabatic Process: No heat exchange, work done changes internal energy.

3. Isobaric Process: Constant pressure, heat supplied partly does work and partly changes internal energy.

4. Isochoric Process: Constant volume, no work done, all heat changes internal energy.

StudentBro notes provide stepwise examples for each process for NEET preparation.

Specific Heats

• At constant volume (C_v): Q = n C_v ΔT

• At constant pressure (C_p): Q = n C_p ΔT

• Relation: C_p − C_v = R (for ideal gases)

• NEET numericals often include heat capacity problems for monoatomic and diatomic gases.

Enthalpy (H)

• Definition: H = U + P V

• Change in enthalpy: ΔH = ΔU + PΔV

• Useful in isobaric processes for calculating heat absorbed

• NEET conceptual questions may ask for relation between ΔH and Q at constant pressure.

Work Done in P–V Diagram

• Area under the P–V curve represents work done

• NEET numericals often include work done in expansion, compression, and cyclic processes.

StudentBro notes provide diagrammatic methods for quick understanding.

Applications for NEET

• Calculating internal energy change in various processes

• Determining work done and heat transferred

• Solving isothermal, adiabatic, isobaric, and isochoric problems

• Understanding thermodynamic cycles such as Carnot cycle

• NEET may include questions connecting first law of thermodynamics with calorimetry and gas laws

Tips for NEET Preparation on Thermodynamics

1. Memorize formulas for ΔU, Q, W, C_v, C_p, and ΔH

2. Understand the direction of heat and work in different processes

3. Solve P–V diagram-based numerical problems for clarity

4. Practice cyclic processes and first law applications

5. Visualize energy flow in isothermal and adiabatic processes

StudentBro notes emphasize stepwise methods and diagrams for better retention.

Advantages of StudentBro NEET Physics Notes

• Covers first law of thermodynamics, internal energy, work, heat, specific heats, and thermodynamic processes

• Includes step-by-step derivations, solved examples, and diagrams

• Structured for easy revision and conceptual clarity

• Focused on NEET syllabus and high-yield problems

These notes ensure aspirants can confidently tackle thermodynamics questions in NEET exams.

Conclusion

The chapter Thermodynamics is a vital part of NEET Physics under heat and energy. Mastery of internal energy, first law of thermodynamics, heat, work, and thermodynamic processes is essential for solving both conceptual and numerical problems.

StudentBro NEET Physics notes provide structured, clear, and exam-focused guidance, enabling aspirants to confidently solve thermodynamics questions and excel in NEET exams.