Consider two insulating sheets with thermal resistances $R_1$ and $R_2$ as shown. The temperatures $\theta $ is
$\frac{{{\theta _1}{\theta _2}{R_1}{R_2}}}{{({R_1} + {R_2})({\theta _1} + {\theta _2})}}$
$\frac{{{\theta _1}{R_1} + {\theta _2}{R_2}}}{{{R_1} + {R_2}}}$
$\frac{{({\theta _1} + {\theta _2})\left( {{R_1}{R_2}} \right)}}{{R_1^2 + R_2^2}}$
$\frac{{{\theta _1}{R_2} + {\theta _2}{R_1}}}{{{R_1} + {R_2}}}$
When thermal conductivity is said to be constant ?
The temperature of the two outer surfaces of a composite slab, consisting of two materials having coefficients of thermal conductivity $K$ and $2K$ and thickness $x$ and $4x$ , respectively are $T_2$ and $T_1$ ($T_2$ > $T_1$). The rate of heat transfer through the slab, in a steady state is $\left( {\frac{{A({T_2} - {T_1})K}}{x}} \right)f$, with $f $ which equal to
The lengths and radii of two rods made of same material are in the ratios $1 : 2$ and $2 : 3$ respectively. If the temperature difference between the ends for the two rods be the same, then in the steady state, the amount of heat flowing per second through them will be in the ratio
If the ratio of coefficient of thermal conductivity of silver and copper is $10 : 9$ , then the ratio of the lengths upto which wax will melt in Ingen Hausz experiment will be
For the figure shown, when arc $ACD$ and $ADB$ are made of same material, the heat carried between $A$ and $B$ is $H$ . If $ADB$ is replaced with another material, the heat carried becomes $2H$ . If the temperatures at $A$ and $B$ are fixed at $T_1$ and $T_2$ , what is the ratio of the new conductivity to the old one of $ADB$