The coefficient of performance (COP) of a refrigerator is defined as the ratio of: a) the difference between the heat expelled to the outside from the heat removed from the inside to the work done to remove the heat.
b) the heat expelled to the outside to the work done to remove the heat.
c) the heat removed from the inside to the heat expelled to the outside.
d) the heat removed from the inside to the work done to remove the heat.
e) the heat expelled to the outside to the heat removed from the inside.

D

Explanation:

Solution:-

- The refrigeration cycle contains the target refrigerated place and the warm reservoir.

- The purpose of the refrigeration cycle is to exchange heat in the evaporator that consists of a cooling fluid mostly ( R - 134a ) with the air in the target refrigerated place.

- The cooling gas in the cycle is at a much lower temperature than the temperature in the target place.

- The exchange of heat is directed from the targeted refrigerated place to the working fluid in the cycle.  

- This is also called the cooling load of the refrigerator / refrigeration cycle ( Ql ).

- The super-heated fluid is then taken to the condenser where heat exchanged with the surrounding which is at much lower temperature than the super-heated fluid in the cycle.  

- Since, both the condenser and evaporator work at different pressures. A compressor is installed to pressurize the working fluid to the condenser pressure. Some amount of energy is required to do work on the working fluid of the cycle. This is denoted as the work input to the cycle. ( Win ).

- The performance of a refrigeration cycle is basically expressed as a ratio of desired out-put and the work-input to the cycle ( compressor ).

- The desired output of the refrigeration cycle is to remove heat from the target place via evaporator. So we express the performance of a refrigeration cycle with a parameter known as the coefficient of performance ( COP ):

- The ratio of cooling load to work-done on the working fluid.

The heat removed from the inside to the work done to remove the heat.

d. platinum would have the greatest temperature increase because it has the lowest specific heat.