A refrigerator removes heat from the interior at a rate of 100 J per cycle and rejects heat to the room at a rate of 150 J per cycle. What is the coefficient of performance (COP) of this refrigerator?

Core Concept

The coefficient of performance (COP) for a refrigerator is defined as COP = Qc/W, where Qc is the heat removed from the cold reservoir and W is the work input. Since energy is conserved, W = Qₕ - Qc, where Qₕ is the heat rejected to the hot reservoir. Thus, COP = Qc/(Qₕ - Qc) = 100 J/(150 J - 100 J) = 100 J/50 J = 2.0.