Even carnot heat engine cannot give `100%` efficiency. Explain why
OR
can you design a heat engine of `100%` efficiency? Explain ypur answer.
OR
A heat engine with `100%` efficiency is only a theoretical possibility. Explain.

Answer

The efficiency of a heat engine,
`eta =1 -(T_(2))/(T_(1))`
The efficiency will be `100% or 1, if T_(2) = 0K`
Since temperature equal to `0K` cannot be reached, a heat engine cannot have `100%` efficiency.