Heat Conduction in One Dimension

  Which one is having the lowest thermal conductivity?

What is the Searle's apparatus?

What is Searle's method for thermal conductivity?

Two heater coils separately take $10 \min$ and $5 \min$ to boil a certain amount of water. If both the coils are connected in series, the time taken to boil water is

Which one of the following is not the example of the athermanous medium.

Which one of the following is not the example of the diathermanous medium.

Three rods (lengths $2l, l, l)$ made of the same material and having the same area of cross-section are joined as shown in figure. The end points $A, B$ and $C$ are maintained at constant temperatures $100°\mathrm{C}, 50°\mathrm{C}$ and $0°\mathrm{C},$ respectively. Assuming that there is no loss of heat from the surface of the rods, find the temperature that the junction $P$ ultimately reaches.

Two rods of the same length and diameter having thermal conductivities $K_1$ and $K_2$ are joined in parallel. The equivalent thermal conductivity of the combination is

A long metallic bar is carrying heat from one of its ends to the other end under a steady state. The variation of temperature $\mathrm{\theta }$ along the length $x$ of the bar from its hot end is best described by which of the following figure?

Two rods (one semi-circular and other straight) of the same material and of same cross-sectional area are joined as shown in the diagram. The points $\mathrm{A}$ and $\mathrm{B}$ are maintained at different temperatures. The ratio of the heat transferred through a cross-section of a semi-circular rod to the heat transferred through a cross-section of the straight rod in a given time is

If the power consumption is $400 \mathrm{W}$,

The thermal conductivity of air is:

A partition wall has two layers of different materials $\mathrm{A}$ and $\mathrm{B}$ in contact with each other. They have the same thickness but the thermal conductivity of layer $\mathrm{A}$ is twice that of $\mathrm{B}$. At steady state, if the temperature difference across the layer $\mathrm{B}$ is $50 \mathrm{K}$, then the corresponding temperature difference across the layer $\mathrm{A}$ is

The thermal conductivity of air is:

The temperature difference of $120 °\mathrm{C}$ is maintained between two ends of a uniform rod $AB$ of length $2L$. Another bent rod $PQ$, of the same cross-section as $AB$ and length $\frac{3L}{2}$, is connected across $AB$ (see figure). In steady-state, the temperature difference between $P$ and $Q$ will be close to

A long metallic bar is carrying 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?

The two ends of a metal rod are maintained at temperatures $100°\mathrm{C}$ and $110°\mathrm{C}.$ The rate of heat flow in the rod is found to be $4.0 \mathrm{J} {\mathrm{s}}^{-1}.$ If the ends are maintained at temperatures $200°\mathrm{C}$ and $210°\mathrm{C},$ the rate of heat flow will be:

The temperature of the two outer surfaces of a composite slab consisting of two materials having thermal conductivities as $K$ and $2K$ of thickness $x$ and $4x$ respectively are $T_2$ and $T_1\left(T_2>T_1\right)$. The rate of heat transfer through the slab in a steady state is $\left(\frac{A\left(T_2-T_1\right)K}{x}\right)f$ with $f$ equal to

The figure shows a system of two concentric spheres of radii $r_1$ and $r_2$ and kept at temperature $T_1$ and $T_2,$ respectively. The radial rate of flow of heat in a substance between the two concentric spheres is proportional to:

Three metal rods made of copper, aluminium and brass, each $20 \mathrm{cm}$ long and $4 \mathrm{cm}$ in diameter, are placed end to end with aluminium between the other two. The free ends of copper and brass are maintained at $100$ and $0°\mathrm{C}$ respectively. Assume that the thermal conductivity of copper is twice that of aluminium and four times that of brass. The equilibrium temperatures of the copper-aluminium and aluminium-brass junctions are respectively-