Question

One of the most efficient engines ever developed operated between 2100K and 700K. Its actual efficiency is 40%. What percentage of its maximum possible efficiency is this?

Answer 1

`T_1=2100K`, `T_2=700K`, `eta_(actual)=40%`
Maximum possible effiency of Carnot engine is
`eta_(max)=1-(T_2)/(T_1)=1-700/2100`
`=0.666=66.6%`
Actual efficiency as the percentage of the maximum possible efficiency is
`(eta_(actual))/(eta_(max))xx100=40/66.6xx100`
`=60%`