The two ends of a metal rod are maintained at temperatures \(100^{\circ}\mathrm{C}\) and \(110^{\circ}\mathrm{C}\). The rate of heat flow in the rod is found to be 4.0 J/s. If the ends are maintained at temperatures \(200^{\circ}\mathrm{C}\) and \(210^{\circ}\mathrm{C}\), the rate of heat flow will be:
1. 44.0 J/s
2. 16.8 J/s
3. 8.0 J/s
4. 4.0 J/s

Subtopic:  Conduction |
 87%
From NCERT
NEET - 2015
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Three rods made of the same material and having the same cross-section have been joined as shown in the figure. Each rod has the same length. The left and right ends are kept at \(0^{\circ}\mathrm{C}\) and \(90^{\circ}\mathrm{C}\), respectively. The temperature at the junction of the three rods will be:

         
1. \(45^{\circ}\mathrm{C}\)
2. \(60^{\circ}\mathrm{C}\)
3. \(30^{\circ}\mathrm{C}\)
4. \(20^{\circ}\mathrm{C}\)

Subtopic:  Conduction |
 84%
From NCERT
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Mud houses are cooler in the summer and warmer in the winter because:

1. the mud is a superconductor of heat.
2. the mud is a good conductor of heat.
3. the mud is a bad conductor of heat.
4. None of the above

Subtopic:  Conduction |
 81%
From NCERT
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Two conducting slabs of heat conductivity \(K_{1} ~  \text{and}   ~K_{2}\) are joined as shown in fig. If the temperature at the ends of the slabs are \(\theta_{1}\  and\  \theta_{2} \ (\theta_{1}   >   \theta_{2} ),  \)then the final temperature \( \left(\theta\right)_{m} \)of the junction will be:

              

1. \(\frac{K_{1} \theta_{1}   +   K_{2} \theta_{2}}{K_{1}   +   K_{2}}\) 2. \(\frac{K_{1} \theta_{2}   +   K_{2} \theta_{1}}{K_{1}   +   K_{2}}\)
3. \(\frac{K_{1} \theta_{2}   +   K_{2} \theta_{1}}{K_{1}   -   K_{2}}\) 4. None
Subtopic:  Conduction |
 83%
From NCERT
AIPMT - 1999
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Two rods, A and B, of different materials having the same cross-sectional area are welded together as shown in the figure. Their thermal conductivities are K1 and K2. The thermal conductivity of the composite rod will be:

   

1. K1+K22
2. 3K1+K22
3. K1+K2
4. 2K1+K2

Subtopic:  Conduction |
 78%
From NCERT
NEET - 2017
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Four rods of the same material with different radii and length l are used to connect two heat reservoirs at different temperatures. In which of the following cases is the heat conduction fastest?

1. r=13cm, l=19cm

2. r = 3 cm, l = 9 cm

3. r = 4 cm, l = 8 cm

4. r = 1 cm, l = 1 cm

Subtopic:  Conduction |
 73%
From NCERT
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When two ends of a rod wrapped with cotton are maintained at different temperatures and, after some time, every point of the rod attains a constant temperature, then:

1. Conduction of heat at different points of the rod stops because the temperature is not increasing
2. The rod is a bad conductor of heat
3. Heat is being radiated from each point of the rod
4. Each point of the rod is giving heat to its neighbour at the same rate at which it is receiving heat
Subtopic:  Conduction |
 75%
From NCERT
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Three rods made of the same material, having the same cross-sectional area but different lengths 10 cm, 20 cm and 30 cm are joined as shown. The temperature of the junction will be:-

   
1. \(10.8^{\circ}\mathrm{C}\)
2. \(14.6^{\circ}\mathrm{C}\)
3. \(16.4^{\circ}\mathrm{C}\)
4. \(18.2^{\circ}\mathrm{C}\)

Subtopic:  Conduction |
 70%
From NCERT
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Two rods (one semi-circular and the other straight) of the same material and of the same cross-sectional area are joined as shown in the figure. Points A and 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 a straight rod at any given point in time will be:
     
1. 2: π 

2. 1: 2

3. π: 2

4. 3: 2

Subtopic:  Conduction |
 66%
From NCERT
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One likes to sit in the sunshine in the winter season, because:

1. The air around the body is hot, and the body absorbs heat from it.
2. we get energy from the sun.
3. we get heat by conduction from the sun.
4. None of the above



 

Subtopic:  Conduction |
 64%
From NCERT
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