- Introduction
- Concept of Heat
- P-V Indicator Digram
- |
- Work in volume changes
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- Internal Energy and first law of thermodynamics
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- Specific heat capacity of an ideal gas
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- Thermodynamic Processes
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- Quasi static Processes
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- Isothermal Process
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- Adiabatic Process
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- Isochoric process
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- Isobaric process
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- Work done in Isothermal process
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- Work done in an Adiabatic process
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- Heat Engine and efficiency
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- Principle of a Refrigerator
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- Second law of thermodynamics
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- Reversibility and irreversibility
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- Carnot's Heat Engine
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- Carnot Theorem
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- Solved Examples

- Only two thermodynamic variables are sufficient to describe a system because third vaiable can be calculated from equation of state of the system.

- P-V Indicator Digram is just a graph between pressure and volume of a system undergoing an operation.

- When a system undergoes an expansion from state A (P
_{1}V_{1}) to a state B (P_{2}V_{2}) its indicator digram is shown as follows.

- In case of compression system at state A(P
_{1}V_{1}) goes to a state B(P_{2}V_{2}) its indicator digram is as follows.

- Intermediate states of system are represented by points on the curve.

- The pressure volume curve for a fixed temperature is called isotherm.

- Consider a cylinder filled with gas and equiped with a movable piston as shown in fig below

fig - Force exerted by a system during small expansion.

Suppose,

A - Cross Sectional area of cylinder

P - Pressure exerted by piston at the piston face.

PA - Force exerted by the system.

- If piston moves out by a distance dx then work done by this force is dW given by

dW = PAdx

= PdV (1)

since V = Adx and dV is change in volume of the system.

- In a finite volume change from V
_{1}to V_{2}

W=∫PdV (2)

where limits of integration goes from V_{1}to V_{2}

Graphically this relationship is shown below

- Thus eqn (2) can be interpreted graphically as area under the curve between limits V
_{1}and V_{2}.

- If pressure remains constant while the volume changes, then work is

W = P(V_{2}-V_{1}) (3)

- Work done not only depends on initial and final states but also on the intermediate states i.e., on the path.

Class 11 Maths Class 11 Physics Class 11 Chemistry

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