The coefficient of performace of a refrigerator is 5. If the temperature inside freezer is - 20^(@)C, the temperature of the surroundings to which it rejects heat is

The coefficient of performace of a refrigerator is 5. If the temperatu

1.	The coefficient of performace of a refrigerator is 5. If the temperature inside freezer is - 20^(@)C, the temperature of the surroundings to which it rejects heat is
Answer» `11^(@)C` `21^(@)C` `31^(@)C` `41^(@)C` Solution :The coefficient of performance of a refrigerator is `alpha = (T_(2))/(T_(1) - T_(2))` where `T_(1)` and `T_(2)` are the temperature of HOT and COLD reservoirs (in kelvin) respectively. Here, `alpha = 5, T_(2) = -20^(@)C = -20 + 273 K = 253 K, T_(1) = ?` `:. 5 = (253 K)/(T_(1) - 253 K)` `5T_(1) - 5(253 K) = 253 K = 6(253 K)` `T_(1) = (6)/(5)(253 K) = 303.6 K = 303.6 - 273 = 30.6^(@) ~~ 31^(@)C`