37.
The efficiency of a Carnot heat engine operating between absolute temperatures T1 and T2 (when, T1 > T2) is given by $$\frac{{{{\text{T}}_1} - {{\text{T}}_2}}}{{{{\text{T}}_1}}}.$$  The co-efficient of performance (C.O.P.) of a Carnot heat pump operating between T1 and T2 is given by