Question

A heat engine is working between 0ºC and 273ºC. What could be its efficiency?
Select one:
a. 25%
b. 100%
c. 50%

Answer 1

Solution

Answer: c. 50%

Since no other information is provided we may assume the engine to be an ideal Carnot engine. Efficiency of ideal Carnot engine is given by,

Where Tc and Th are the temperature in Kelvin scale of cold and hot reservoirs of engine. Here the lowest temperature is 0°C which is the temperature of cold reservoir.

The highest temperature is 273° thus temperature of hot reservoir,

Thus efficiency,