The temperature of the ice-box of a refrigerator is `-7^(@)C` and the room temperature is `31^(@)C`. To maintain the temperature of the ice-box, the refrigerator approximates a Carnot refrigerator, what is its power consumption?

Explanation

Temperature of the ice-box = `(-7+273)K = 266K`
Temperature of the surrounding = `(31 + 273) K = 304 K`
`:.` Coefficient of performance,
`e = (T_2)/(T_(1)-T_(2)) = (266)/(304-266) = (266)/(38) = 7`
Again, `e = (Q_2)/(W)`
`:. W = (Q_2)/e = (20000)/7 cal cdot "min"^(-1)`
`=(20000 xx 4.2)/(7 xx 60) J cdot s^(-1) = 200 J cdot s^(-1)`
`=200 W`.