The co-efficient of performance (COP) of a refrigerating system, which is its index of performance, is defined as the ratio of useful refrigeration to the net work. The units of __________ and COP are the same.

Answer: Option D

COP of refrigerating system $$=\frac{\text{heat taken from the low temperature reserviour}}{\text{work supplied}}$$

So, we can say there are no units for COP because the heat taken and work both are energy in transits and therefore have same units.