Q. No.The flow of heat from one end at higher temperature to the end at lower temperature of a body is by the virtue of:
| 1. | density gradient |
| 2. | temperature gradient |
| 3. | velocity gradient |
| 4. | none of these |
Subtopic: Conduction |
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The two ends of a rod of length L and a uniform cross-sectional area A are kept at two temperatures T1 and T2 (T1> T2). The rate of heat transfer through the rod in a steady state is given by:
1.
2.
3.
4.
Subtopic: Conduction |
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Level 1: 80%+
AIPMT - 2009
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Equal temperature differences exist between the ends of two metallic rods 1 and 2 of equal lengths. Their thermal conductivities are K1 and K2 and their areas of the cross-section are A1 and A2 respectively. The condition of equal rate of heat transfer is:
1. K1A2 = K2A1
2. K1A1 = K2A2
3.
4.
Subtopic: Conduction |
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\(K_1\) and \(K_2\) are the thermal conductivities, \(L_1\) and \(L_2\) are the lengths, and \(A_1\) and \(A_2\) are the cross-sectional areas of steel and copper rods respectively such that \(\dfrac{K_{2}}{K_{1}}=9, \dfrac{A_{1}}{A_{2}}=2~\text{and}~ \dfrac{L_{1}}{L_{2}}=2.\) Then, for the arrangement as shown in the figure, the value of the temperature \(T\) of the steel–copper junction in the steady-state will be:
1. \(18^\circ \text{C}\)
2. \(14^\circ \text{C}\)
3. \(45^\circ \text{C}\)
4. \(150^\circ \text{C}\)
1. \(18^\circ \text{C}\)
2. \(14^\circ \text{C}\)
3. \(45^\circ \text{C}\)
4. \(150^\circ \text{C}\)
Subtopic: Conduction |
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Level 1: 80%+
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Given below are two statements:
| Assertion (A): | Thermal conduction occurs only in the presence of a temperature gradient. |
| Reason (R): | In the absence of a temperature gradient (i.e., no temperature difference in space), thermal energy – which is transferred due to molecular (or particle) collisions, cannot be transferred in any particular direction. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | (A) is False but (R) is True. |
Subtopic: Conduction |
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Level 1: 80%+
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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 is of the same length. The left and right ends are kept at \(0^\circ \text{C}\) and \(90^\circ \text{C}\) respectively. The temperature of the junction of the three rods will be:
| 1. | \(45^\circ \text{C}\) | 2. | \(60^\circ \text{C}\) |
| 3. | \(30^\circ \text{C}\) | 4. | \(20^\circ \text{C}\) |
Subtopic: Conduction |
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Which of the following circular rods, (given radius \(r\) and length \(l\)) each made of the same material and whose ends are maintained at the same temperature will conduct the most heat:
| 1. | \(r=2r_0;~l=2l_0\) |
| 2. | \(r=2r_0;~l=l_0\) |
| 3. | \(r=r_0;~l=2l_0\) |
| 4. | \(r=r_0;~l=l_0\) |
Subtopic: Conduction |
86%
Level 1: 80%+
AIPMT - 2005
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The thermal conductivity of a rod depends on
1. length
2. mass
3. area of cross section
4. material of the rod.
Subtopic: Conduction |
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Three identical thermal conductors are connected, as shown in the figure. The temperature of the connected junction is (assuming no heat lost due to radiation):
1. \(60^\circ\text{C}\)
2. \(20^\circ\text{C}\)
3. \(50^\circ\text{C}\)
4. \(10^\circ\text{C}\)
1. \(60^\circ\text{C}\)
2. \(20^\circ\text{C}\)
3. \(50^\circ\text{C}\)
4. \(10^\circ\text{C}\)
Subtopic: Conduction |
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Given below are two statements:
| Assertion (A): | When the temperature difference across the two sides of a wall is increased, its thermal conductivity remains constant. |
| Reason (R): | Thermal conductivity depends on nature of the material of the wall. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | Both (A) and (R) are False. |
Subtopic: Conduction |
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