What should be the condition for the efficiency of a Carnot engine to be equal to 1?
Efficiency of Carnot engine, `eta=W/Q_1=(Q_1-Q_2)/Q_1`
W = Work done by the engine
Q1 = Heat abstracted from the source
Q2 = Heat transferred to the sink
Thus, for `eta=1, W=Q_1" or " Q_2=0,` the total heat which is abstracted from the source gets converted into work.