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 ${K}_{1}$ and ${K}_{2}$. The thermal conductivity of the composite rod will be:

1. $\frac{{K}_{1}+{K}_{2}}{2}$

2. $\frac{3\left({K}_{1}+{K}_{2}\right)}{2}$

3. ${K}_{1}+{K}_{2}$

4. $2\left({K}_{1}+{K}_{2}\right)$

Subtopic: Conduction |

78%

From NCERT

NEET - 2017

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Four rods of the same material with different radii *r *and length $\mathcal{l}$* *are used to connect two heat reservoirs at different temperatures. In which of the following cases is the heat conduction fastest?

1. $r=\frac{1}{3}\mathrm{cm},$ $\mathcal{l}=\frac{1}{9}\mathrm{cm}$

2. *r* = 3 cm, *$\mathcal{l}$* = 9 cm

3. *r* = 4 cm, *$\mathcal{l}$* = 8 cm

4. *r* = 1 cm, *$\mathcal{l}$* = 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: $\mathrm{\pi}$

2. 1: 2

3. $\mathrm{\pi}$: 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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