Embibe Experts Solutions for Chapter: Heat Transfer, Exercise 3: Exercise-3

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:

A body cools from a temperature $3T$ to $2T$ in $10 \mathrm{minutes}$. The room temperature is $T$. Assume that Newton's law of cooling is applicable. The temperature of the body at the end of the next $10 \mathrm{minutes}$ will be

Two rods $A$ and $B$ of different materials are welded together as shown in the figure. Their thermal conductivities are $K_1$ and $K_2$. The thermal conductivity of the composite rod will be

$1 \mathrm{kcal}$ of heat flowing through a rod of iron per second. When the rod is cut down to $4$ pieces then what will be the heat flowing through each piece per second having the same differential temperature (temperature gradient)?

Black holes in orbit around a normal star are detected from the earth due to the frictional heating of infalling gas into the black hole, which can reach temperatures greater than ${10}^6 \mathrm{K}$. Assuming that the infalling gas can be modelled as a blackbody radiator then the wavelength of maximum power lies

Two conductors having the same width and length, thickness $d_1$ and $d_2$ thermal conductivity $K_1$ and $K_2$ are placed one above the other. Find the equivalent thermal conductivity.

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 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