Question

A Carnot engine, whose efficiency is 40% takes heat from a source maintained at temperature 600K. To have an efficiency 60%, the intake temperature for the same exhaust temperature should be

• A. \(1800\) K
• B. \(900\) K
• C. \(720\) K
• D. \(360\) K

Hint:

Use \(\eta=1-\dfrac{T_2}{T_1}\) with the same exhaust temperature.

Answer 1

The Correct Option is B

Step 1: Use the ratio form
$\dfrac{T_2}{T_1}=1-\eta$. Initially $\dfrac{T_2}{600}=0.6$.

Step 2: Second case
$T_2=360$ K, and $\dfrac{360}{T_1'}=0.4$ gives $T_1'=900$ K, option (B).

Final Answer:
The intake temperature is 900 K, option (B). \[ \boxed{900\ \text{K}} \]