A Carnot engine has efficiency 1/6. After sink temperature is lowered by 65 K, efficiency becomes 1/3. If final sink temperature is P×65 K, find P.
Physics · Mixed Chapter
JEE Main Practice

Question

A Carnot engine has efficiency 1/6. After sink temperature is lowered by 65 K, efficiency becomes 1/3. If final sink temperature is P×65 K, find P.

G1 Physics · Accepted Answer

Step 1: η=1−Tᶜ/Tʰ. Initially 1/6⇒Tᶜ₁=(5/6)Tʰ. Step 2: Finally 1/3⇒Tᶜ₂=(2/3)Tʰ. Step 3: Difference Tᶜ₁−Tᶜ₂=(5/6−2/3)Tʰ=Tʰ/6=65⇒Tʰ=390 K. Step 4: Final sink temperature Tᶜ₂=(2/3)×390=260 K=4×65 K. The PDF prints 5; source key conflicts with direct Carnot calculation.