In a refrigerator one removes heat from a lower temperature and deposits to the surroundings at a higher temperature. In this process, mechanical work has to be done, which is provided by an electric motor. If the motor is of 1kW power and heat transferred from `-3^(@)` C to `27^(@)` C, find the heat taken out of the refrigerator per second assuming its efficiency is 50% of a perfect engine.

Options

A. `5 kJ`
B. `6 kJ`
C. `19 kJ`
D. `20 kJ`

Answer

D

Explanation

In an refrigerator ………….
Efficiency of ideal engine
`eta = 1- (270)/(300) = (1)/(10)`
Efficiency of refrigerator `= (1)/(20)`
`(1)/(20) = (1kJ)/(Q) implies Q_(1) = 20 kJ`