1
A scientist says that the efficiency of his heat engine which works at source temperature 127 and sink temperature 27 is 26\%, then
- it is impossible
- it is possible but less probable
- it is quite probable
- data are incomplete.
Answer
(1) it is impossible
Solution
T1 = 127 + 273 = 400 K, T2 = 27 + 273 = 300 K
Maximum (Carnot) efficiency: = 1 - T2T1 = 1 - 300400 = 0.25 = 25\%
No engine working between two temperatures can be more efficient than a Carnot engine (Carnot's theorem)
An efficiency of 26\% > 25\% is impossible.
Answer: (1)
AIPMT 2001