Explain what do you understand by the efficiency of a heat engine?

thermodynamics
cbse

#1

The efficiency of a heat engine is stated as the ratio of the net work done by the heat engine and heat absorbed by the working substance.
Suppose a heat engine absorbs ${ Q }{ 1 }$ heat from the hot reservoir and gives
${ Q }
{ 2 }$ heat to the colder reservoir. So, the work done by the working substance is