INDICATOR DIAGRAM

Options

A. P -T curve
B. P - V curve
C. V - T curve
D. Q -T curve

Answer

### Step-by-Step Solution:

1. **Understanding the Indicator Diagram**:
- An indicator diagram is a graphical representation of the relationship between pressure (P) and volume (V) of a gas during a thermodynamic process.

2. **Axes of the Diagram**:
- In the indicator diagram, the x-axis represents the volume (V) of the gas, while the y-axis represents the pressure (P).

3. **Plotting the Curve**:
- As the gas undergoes different thermodynamic processes (like isothermal, adiabatic, isochoric, or isobaric), the points representing the pressure and volume will change. These points can be plotted on the graph to form a curve.

4. **Shape of the Curve**:
- The shape of the curve will depend on the specific thermodynamic process the gas is undergoing. For example:
- An isothermal process will show a hyperbolic curve.
- An adiabatic process will show a steeper curve compared to isothermal.

5. **Area Under the Curve**:
- The area enclosed by the curve and the volume axis (x-axis) represents the work done by or on the gas during the process.
- Mathematically, the work done (W) can be expressed as:
\[ W = \int P \, dV \]
- This integral calculates the area under the curve in the PV diagram.

6. **Conclusion**:
- The indicator diagram is crucial for visualizing the work done in thermodynamic processes and understanding the behavior of gases under various conditions.