D. C. Pandey Solutions for Chapter: Calorimetry and Heat Transfer, Exercise 1: Objective Problems

Three identical rods $A, B$ and $C$ are placed end to end. A temperature difference is maintained between the free ends of $A$ and $C$. The thermal conductivity of $B$ is thrice that of $C$ and half of that of $A$. The effective thermal conductivity of the system will be $(K_{\mathrm{A}}$ is the thermal conductivity of rod $A)$

$1.56\times {10}^5 \mathrm{J}$ of heat is conducted through is $2 {\mathrm{m}}^2$ wall of $12 \mathrm{cm}$ thick in one hour. Temperature difference between the two sides of the wall is $20°\mathrm{C}$. The thermal conductivity of the material of the wall is (in $\mathrm{W} {\mathrm{m}}^{-1} {\mathrm{K}}^{-1}$)

A piece of ice (specific heat capacity $=2100 \mathrm{J} {\mathrm{kg}}^{-1}{}^{\circ }\mathrm{C}^{-1}$ and latent heat $=3.36\times {10}^5 \mathrm{J} {\mathrm{kg}}^{-1}$) of mass $m \mathrm{gram}$ is at $-5°\mathrm{C}$ at atmospheric pressure. It is given $420 \mathrm{J}$ of heat, so that the ice starts melting. Finally, when the ice-water mixture is in equilibrium, it is found that $1 \mathrm{g}$ of ice has melted. Assuming there is no other heat exchange in the process, the value of $m$ is

Two spherical bodies $A$ (radius $6 \mathrm{cm}$) and $B$ (radius $18 \mathrm{cm}$) are at temperatures $T_1$ and $T_2$, respectively. The maximum intensity in the emission spectrum of $A$ is at $500 \mathrm{nm}$ and in that of $B$ is at $1500 \mathrm{nm}$. Considering them to be black bodies, what will be the ratio of the rate of total energy radiated by $A$ to that of $B$?

A long metallic bar is carrying heat from one of its ends to the other end under 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 figures?

Two slabs are of the thicknesses $d_1$ and $d_2$. Their thermal conductivities are $K_1$ and $K_2$ respectively, they are in series. The free ends of the combination of these two slabs are kept at temperatures ${\theta }_1$ and ${\theta }_2$. Assume ${\theta }_1>{\theta }_2$. The temperature $\theta$ of their common junction is

For an opaque body, coefficient of transmission is

Two spheres of radii $8 \mathrm{cm}$ and $2 \mathrm{cm}$ are cooling. Their temperatures are $127 °\mathrm{C}$ and $527 °\mathrm{C}$ respectively. Find the ratio of energy radiated by them at the same time.