d
\({P_1} = \frac{{{{(220)}^2}}}{{{R_1}}}\) અને \({P_2} = \frac{{{{(220 \times 0.8)}^2}}}{{{R_2}}}\)

\(\frac{{{P_2}}}{{{P_1}}} = \frac{{{{(220 \times 0.8)}^2}}}{{{{(220)}^2}}} \times \frac{{{R_1}}}{{{R_2}}}\,\,\)  

\( \Rightarrow \,\,\frac{{{P_2}}}{{{P_1}}} = {(0.8)^2} \times \frac{{{R_1}}}{{{R_2}}}.\,\)  \({R_2}\, < \,\,{R_1}\)

(વોલ્ટેજ \(220\ V \to 220 \times 0.8 V\) ઘટતો હોવાથી ઉત્પન્ન થતી ઉષ્મા ઘટે છે.)

માટે \(\frac{{{R_1}}}{{{R_2}}} > 1\,\,\,\,\)  \( \Rightarrow \,\,{P_2} > {(0.8)^2}{P_1}\,\,\)

\( \Rightarrow \,\,\,{P_2} > {(0.8)^2} \times 100\,W\)

\( \Rightarrow \,\,\) માટે  \( \,\,\frac{{{P_2}}}{{{P_1}}} = \frac{{(220 \times 0.8){i_2}}}{{220\,{i_1}}},\,\,{i_2} < {i_1}\)

માટે  \(\,\frac{{{P_2}}}{{{P_1}}} < 0.8\,\,\) \( \Rightarrow \,\,{P_2} < (100 \times 0.8)\)

માટે સાચો પાવર \(100 \times (0.8)^2\ W\) અને (\(100 \times 0.8)\, W\)  વચ્ચે હશે.