In the Ingen Hauz’s experiment the wax melts up to lengths $10$ and $25 cm$ on two identical rods of different materials. The ratio of thermal conductivities of the two materials is
$1:6.25$
$6.25 : 1$
$1:\sqrt {2.5} $
$1:2.5$
There are two identical vessels filled with equal amounts of ice. The vessels are of different metals., If the ice melts in the two vessels in $20$ and $35$ minutes respectively, the ratio of the coefficients of thermal conductivity of the two metals is
A cylindrical rod with one end in a steam chamber and the other end in ice results in melting of $0.1$ gm of ice per second. If the rod is replaced by another with half the length and double the radius of the first and if the thermal conductivity of material of second rod is $\frac{1}{4}$ that of first, the rate at which ice melts in $gm/\sec $will be
Two rectangular blocks, having indentical dimensions, can be arranged either in configuration $I$ or in configuration $II$ as shown in the figure, On of the blocks has thermal conductivity $k$ and the other $2 \ k$. The temperature difference between the ends along the $x$-axis is the same in both the configurations. It takes $9\ s$ to transport a certain amount of heat from the hot end to the cold end in the configuration $I$. The time to transport the same amount of heat in the configuration $II$ is :
Two rods having thermal conductivity in the ratio of $5 : 3$ having equal lengths and equal cross-sectional area are joined by face to face. If the temperature of the free end of the first rod is $100°C$ and free end of the second rod is $20°C$ . Then temperature of the junction is...... $^oC$
The heat is flowing through a rod of length $50 cm$ and area of cross-section $5c{m^2}$. Its ends are respectively at ${25^o}C$ and ${125^o}C$. The coefficient of thermal conductivity of the material of the rod is $0.092 kcal/m×s×^\circ C$. The temperature gradient in the rod is