Question

Which one of the figures correctly represents the T–S diagram of a Carnot engine? 

• A. (A)
• B. (B)
• C. (C)
• D. (D)

Hint:

A real Carnot cycle always looks like a rectangle in the T–S plane: horizontal isotherms and vertical adiabats.

Answer 1

The Correct Option is B

Step 1: Recall the Carnot cycle in the T–S plane.
A Carnot cycle consists of two isothermal processes and two adiabatic processes. In a T–S diagram: - Isothermals appear as horizontal lines (constant temperature).
- Adiabatic processes appear as vertical lines (since entropy remains constant).

Step 2: Identify the correct rectangular shape.
A Carnot engine forms a perfect rectangle in the T–S plane: - Top and bottom edges: isothermal expansion and compression.
- Left and right edges: adiabatic compression and expansion.

Step 3: Compare with the given diagrams.
Only diagram (B) shows a proper rectangle with horizontal and vertical sides, matching the structure of a Carnot cycle.

Step 4: Conclusion.
Thus the correct T–S diagram for a Carnot engine is option (B).