In a composite rod, when two rods of different lengths $l_1$ and $l_2$ and of the same cross-sectional area are joined from end to end then if $K$ is the effective coefficient of thermal conductivity, the value of $(l_1 + l_2)/K$ is
In a composite rod, when two rods of different lengths $l_1$ and $l_2$ and of the same cross-sectional area are joined from end to end then if $K$ is the effective coefficient of thermal conductivity, the value of $(l_1 + l_2)/K$ is
- A
$\frac{{{l_1}}}{{{K_1}}} + \frac{{{l_2}}}{{{K_2}}}$
- B
$\frac{{{l_1}}}{{{K_2}}} + \frac{{{l_2}}}{{{K_1}}}$
- C
$\frac{{{l_1}}}{{{K_1}}} - \frac{{{l_2}}}{{{K_2}}}$
- D
$\frac{{{l_1}}}{{{K_2}}} - \frac{{{l_2}}}{{{K_1}}}$
Similar Questions
Certain quantity of water cools from $70\,^oC$ to $60\,^oC$ in first $10\, minutes$ and to $54\,^oC$ in the next $10\, minutes$. The temperature of the surrounding is ......... $^oC$
Certain quantity of water cools from $70\,^oC$ to $60\,^oC$ in first $10\, minutes$ and to $54\,^oC$ in the next $10\, minutes$. The temperature of the surrounding is ......... $^oC$
Steam is passed into $22\, g$ of water at $20\,^oC$ . The mass of water that will be present when the water acquires a temperature of $90\,^oC$ is ............ $\mathrm{gm}$ (Latent heat of steam is $540\, cal/gm$)
Steam is passed into $22\, g$ of water at $20\,^oC$ . The mass of water that will be present when the water acquires a temperature of $90\,^oC$ is ............ $\mathrm{gm}$ (Latent heat of steam is $540\, cal/gm$)
The power radiated by a black body is $P$ and it radiates maximum energy around the wavelength $\lambda_0$. If the temperature of the black body is now changed so that it radiates maximum energy around wavelength $\frac{3}{4}\lambda_0$, the power radiated by it will increase by a factor of
The power radiated by a black body is $P$ and it radiates maximum energy around the wavelength $\lambda_0$. If the temperature of the black body is now changed so that it radiates maximum energy around wavelength $\frac{3}{4}\lambda_0$, the power radiated by it will increase by a factor of
A cylindrical metallic rod in thermal contact with two reservoirs of heat at its two ends conducts an amount of heat $Q$ in time $t$. The metallic rod is melted and the material is formed into a rod of half the radius of the original rod. What is the amount of heat conducted by the new rod, when placed in thermal contact with same two reservoirs in time $t$
A cylindrical metallic rod in thermal contact with two reservoirs of heat at its two ends conducts an amount of heat $Q$ in time $t$. The metallic rod is melted and the material is formed into a rod of half the radius of the original rod. What is the amount of heat conducted by the new rod, when placed in thermal contact with same two reservoirs in time $t$
The temperature of body is increased from $27\,^oC$ to $127\,^oC$ the radiation emitted by it increases by a factor of
The temperature of body is increased from $27\,^oC$ to $127\,^oC$ the radiation emitted by it increases by a factor of