d
Temperature inside refrigerator \( = {t_2}{\,^ \circ }C\)

Room temperature \( = {t_1}{\,^ \circ }C\)

For refrigerator,

\(\frac{{Heat\,given\,to\,high\,temperature\,\left( {{Q_1}} \right)}}{{Heat\,taken\,from\,lower\,temperature\,\left( {{Q_2}} \right)}} = \frac{{{T_1}}}{{{T_2}}}\)

\(\frac{{{Q_1}}}{{{Q_2}}} = \frac{{{t_1} + 273}}{{{t_2} + 273}}\)

\( \Rightarrow \frac{{{Q_1}}}{{{Q_1} - W}} = \frac{{{t_1} + 273}}{{{t_2} + 273}}\,\,or\,\,1 - \frac{W}{{{Q_1}}} = \frac{{{t_2} + 273}}{{{t_1} + 273}}\)

\(or\,\,\frac{W}{Q_1} = \frac{{{t_1} - {t_2}}}{{{t_1} + 273}}\)

The amount of heat delivered to the room for each joule pf electrical energy \(\left( {W = 1\,J} \right)\)

\({Q_1} = \frac{{{t_1} + 273}}{{{t_1} - {t_2}}}\)