Question

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

A. $$16.8\,J/s$$
B. $$8.0\,J/s$$
C. $$4.0\,J/s$$  
D. $$44.0\,J/s$$
Answer :   $$4.0\,J/s$$
Solution :
As the temperature difference $$\Delta T = {10^ \circ }C$$   as well as the thermal resistance is same for both the cases, so thermal current or rate of heat flow will also be same for both the cases.

Releted MCQ Question on
Heat and Thermodynamics >> Conduction

Releted Question 1

A wall has two layers $$A$$ and $$B,$$ each made of different material. Both the layers have the same thickness. The thermal conductivity of the meterial of $$A$$ is twice that of $$B.$$ Under thermal equilibrium, the temperature difference across the wall is $${36^ \circ }C.$$  The temperature difference across the layer $$A$$ is

A. $${6^ \circ }C$$
B. $${12^ \circ }C$$
C. $${18^ \circ }C$$
D. $${24^ \circ }C$$
Releted Question 2

Three rods of identical cross - sectional area and made from the same metal from the sides of an isosceles triangle $$ABC,$$  right - angled at $$B.$$ The points $$A$$ and $$B$$ are maintained at temperatures $$T$$ and $$\left( {\sqrt 2 } \right)$$  $$T$$ respectively. In the steady state, the temperature of the point $$C$$ is $${T_c}.$$  Assuming that only heat conduction takes place, $$\frac{{{T_c}}}{T}$$ is

A. $$\frac{1}{{2\left( {\sqrt 2 - 1} \right)}}$$
B. $$\frac{3}{{\sqrt 2 + 1}}$$
C. $$\frac{1}{{\sqrt 3 \left( {\sqrt 2 - 1} \right)}}$$
D. $$\frac{1}{{\sqrt 2 + 1}}$$
Releted Question 3

Three rods made of same material and having the same cross-section have been joined as shown in the figure. Each rod is of the same length. The left and right ends are kept at $${0^ \circ }C$$  and $${90^ \circ }C$$  respectively. The temperature of the junction of the three rods will be
Conduction mcq question image

A. $${45^ \circ }C$$
B. $${60^ \circ }C$$
C. $${30^ \circ }C$$
D. $${20^ \circ }C$$
Releted Question 4

Two identical rods are connected between two containers one of them is at $${100^ \circ }C$$  and another is at $${0^ \circ }C.$$  If rods are connected in parallel then the rate of melting of ice is $${q_1}\,gm/sec.$$   If they are connected in series then the rate is $${{q_2}}.$$ The ratio $$\frac{{{q_2}}}{{{q_1}}}$$ is

A. 2
B. 4
C. $$\frac{1}{2}$$
D. $$\frac{1}{4}$$

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Conduction


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