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

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

\(\frac{{{K_1}}}{{{K_2}}}\,\, = \,\,\frac{2}{5}\) અથવા \({K_1} = \,\,\frac{2}{5}\,\,{K_2}\)

સમીકરણ \((i)\) પરથી,\(\,\frac{{2/5\,\,{K_2}A\,\,( - 20 - \theta )}}{{0.02}}\,\,\, = \,\,\frac{{{K_2}A\,\,(\theta  - 20)}}{{0.05}}\)

\( - 20\,\, - \,\,\theta \,\, = \,\,\,\theta \,\, - \,\,20\) અથવા \(\, - 2\theta \,\, = \,\,0\,\,\,\,\,\therefore \,\, \theta \,\,\, = \,\,{0^ \circ }C\)