Law Of Thermal Conductivity - Practice Questions & MCQ

Temperature difference of $120^{\circ} \mathrm{C}$ is maintained between two ends of a uniform rod AB of length 2 L. The $ \frac{3 L}{2}$ is connected across AB (See figure). In another bent rod $P Q$, of the same cross-section as $A B$ and length $\overline{2}$, is connected across $A B$ (See figure). In steady state, temperature(in ${ }^0 \mathrm{C}$ ) difference between P and Q will be close to :

Two thin metallic spherical shells of radii $r_1$ and $r_2\left(r_1<r_2\right)$ are placed with their centres coinciding. A material of thermal conductivity K is filled in the space between the shells. The inner shell is maintained at temperature $\theta_1$ and the outer shell at temperature $\theta_2\left(\theta_1<\theta_2\right)$. The rate at which heat flows radially through the material is :

A long metallic bar carries heat from one of its ends to the other end under steady state. The variation of temperature $\Theta$ along the length $x$ of the bar from its hot end is best described by which of the following figures?

 Three rods of Copper, Brass and Steel are welded together to form a Y - shaped structure.  Area of cross - section of each    rod = 4 cm². End of copper rod is maintained at 100⁰C where as ends of brass and steel are kept at 0⁰C. Lengths of the copper, brass and steel rods are 46, 13 and 12 cms respectively. The rods are thermally insulated from surroundings except at ends. Thermal conductivities of copper, brass and steel are 0.92, 0.26 and 0.12 CGS units respectively. Rate of heat flow through copper rod is :

A metal rod of length $L$ and cross-sectional area $A$ has a thermal conductivity $K$. If the temperature difference between its ends is $\Delta T$, what is the rate of heat conduction through the rod?

Three rods are arranged in series combination with their length , area and conductivity given in the figure , then their thermal resistance is 

Two plates A and B have thermal conductivities 84 Wm^-1 K^-1 and 126 Wm^-1K^-1 respectively. They have same surface area and same thickness. They are placed in contact along their surfaces. If the temperatures of the outer surfaces of A and B are kept at 100^oC and 0^oC respectively, then the temperature of the surface of contact in steady state is ______ ^oC.

A compound consisting of two different materials of thermal conductivity K and 3K respectively. If the two slab have equal thickness then the equivalent thermal conductivity of the series combination of compound slab is 

In which case thermal conductivity is in increasing order 

The coefficient of thermal conductivity depend upon