Calculate η_max for Th = 800 K and Tc = 300 K.

Calculate η_max for Th = 800 K and Tc = 300 K.

• A. 0.375
• B. 0.50
• C. 0.60
• D. 0.625

Answer: (D)

The maximum possible efficiency of a heat engine operating between two reservoirs is given by Carnot efficiency: η_max = 1 − Tc/Th. Here both temperatures are in Kelvin, so the ratio is θ = Tc/Th = 300/800 = 0.375. Subtracting from 1 gives η_max = 1 − 0.375 = 0.625, which is 62.5%. This represents the upper limit for any real engine between these temperatures; actual efficiencies will be lower due to irreversibilities in real processes.

The maximum possible efficiency of a heat engine operating between two reservoirs is given by Carnot efficiency: η_max = 1 − Tc/Th. Here both temperatures are in Kelvin, so the ratio is θ = Tc/Th = 300/800 = 0.375. Subtracting from 1 gives η_max = 1 − 0.375 = 0.625, which is 62.5%.

This represents the upper limit for any real engine between these temperatures; actual efficiencies will be lower due to irreversibilities in real processes.