\(\frac{Q}{t}\,\, = \,\,\,\frac{{{K_1}A\,({\theta _1} - \theta )}}{{{L_1}}}\,\, = \,\,\frac{{{K_2}A\,\,(\theta  - {\theta _2})}}{{{L_2}}}\,\,\,\,\,\,........\,\,\,(1)\)

અહી  \(\theta_1 = -20°C, \theta_2 = 20°C, L_1 = 2 cm = 0.02 m, L_2 = 5 cm = 0.05 m\) અને \(K_1 = K_2 = K.\)

\(\therefore\) સમીકરણ \(\,(i)\,\,\, \frac{{KA( - 20\,\, - \,\,\theta )}}{{0.02}}\,\,\, = \,\,\frac{{KA\,\,(\theta  - 20)}}{{0.05}}\,\) થશે

\(\therefore\) \(5 (-20 - \theta) = 2 (\theta - 20)\)

\(\Rightarrow  -100 - 5 \theta = 2 \theta - 40  \)

\(\Rightarrow  7 \theta = -60\)

\(\Rightarrow  \theta = -8.6 °C\)