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10-2.Transmission of Heat
normal
Two rods having same area are used to connect two reservoirs at temperature $100\,^oC$ and $0\,^oC$ as shown. The temperature of junction is $70\,^oC$. If the rods are now interchanged, the temperature of junction will be ......... $^oC$
A
$70$
B
$30$
C
$50$
D
$40$
Solution
$\frac{100-0}{R_{1}+R_{2}}=\frac{100-70}{R_{1}}=\frac{70-0}{R_{2}}$
$\frac{100}{R_{1}+R_{2}}=\frac{30}{R_{1}}=\frac{70}{R_{2}}$ $…(1)$
When rods are interchanged
$\frac{100-0}{R_{1}+R_{2}}=\frac{100-T}{R_{2}}$
$\frac{70}{\mathrm{R}_{2}}=\frac{100-\mathrm{T}}{\mathrm{R}_{2}} \Rightarrow \mathrm{T}=30^{\circ} \mathrm{C}$
Standard 11
Physics
