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:

Three rods $AB, BC$ and $BD$ of same length $l$ and cross-sectional area $A$ are arranged as shown. The end $D$ is immersed in ice whose mass is $440 \mathrm{g}$ and is at $0{}^{\circ }\mathrm{C}$. The end $C$ is maintained at $100°\mathrm{C}$. Heat is supplied at constant rate of $200 \mathrm{cal} {\mathrm{s}}^{-1}$. Thermal conductivities of $AB, BC$ and $BD$ are $K, 2K$ and $\frac{K}{2}$, respectively. Time after which whole ice will melt is $\left(K=100 \mathrm{cal}/\mathrm{m}-\mathrm{s}-{}^{\circ }\mathrm{C}, A=10{ \mathrm{cm}}^2, l=1 \mathrm{m}\right)$

In the given diagram, the possible direction of heat energy transformation is

In steady state heat conduction, the equations that determine the heat current $j\left(r\right)$ [heat flowing per unit time per unit area] and temperature $T\left(r\right)$ in space are exactly the same as those governing the electric field $E\left(r\right)$ and electrostatic potential $V\left(r\right)$ with the equivalence given in the table below.

A copper rod of length $2.5 \mathrm{m}$ and an iron rod of length $1.5 \mathrm{m}$ having the same areas of cross section are connected in series. Thermal conductivities of copper and iron are respectively $400$ and $80$ $\mathrm{SI}$ units. The equivalent conductivity of the composite bar in $\mathrm{SI}$ unit is ____.

Heat is passed through two cylindrical rods of same material. Their diameters and lengths are in the ratio $1:2$ and $2:1$ respectively. If their ends are maintained at same temperature difference, the ratio of rate of flow of heat through them is

A long rod has one end at $0°\mathrm{C}$ and other end at a high temperature. The coefficient of thermal conductivity varies with distance $x$ from the low temperature end as, $k=k_0\left(1+ax\right)$, where $k_0={10}^2$ SI unit and $a=1 {\mathrm{m}}^{-1}$. At what distance from the first end, the temperature will be $100°\mathrm{C}$? The area of cross-section is $1 {\mathrm{cm}}^2$ and rate of heat conduction is $1 \mathrm{W}$.