Q. No.Ice (\(0^{\circ}\)C) is kept in an insulated reservoir with an opening that is covered at the top with a cloth. When a black cloth \((B)\) is placed at the top, the ice melts at \(2\) g/\(3\) min. When an ordinary cloth \((G)\) is placed, the rate of melting is \(2\) g /\(5\) min. The emissivity of \(G\) is: (assuming that \(B\) behaves as a blackbody)
1.
\(0.6\)
2.
\(0.3\)
3.
\(0.4\)
4.
\(0.5\)
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1. \(600^{\circ} \text{C}\)
2. \(620^{\circ} \text{C}\)
3. \(680^{\circ} \text{C}\)
4. \(520^{\circ} \text{C}\)
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| 1. | is \(2\alpha\) |
| 2. | is \(4\alpha\) |
| 3. | can be any value between \(\alpha\) and \(3\alpha\) |
| 4. | can be any value between \(2\alpha\) and \(3\alpha\) |
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1. \(40\) g
2. \(90\) g
3. \(310\) g
4. \(360\) g
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| 1. | \(l+\Delta l\) | 2. | \(l+\dfrac{\Delta l}{2}\) |
| 3. | \(l+\dfrac{\Delta l}{4}\) | 4. | \(l+\dfrac{3\Delta l}{4}\) |
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| 1. | increases by a factor of \(4\) |
| 2. | increases by a factor of \(2\) |
| 3. | remains unchanged |
| 4. | decreases by a factor of \(2\) |
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1. \(40^\circ\)C
2. \(50^\circ\)C
3. \(60^\circ\)C
4. \(45^\circ\)C
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| 1. | \((^\circ\text C)^ {-1}\) | 2. | \(\text{m}^3/^\circ\text C\) |
| 3. | \(^\circ\text C\) | 4. | \(^\circ\text C/\text{m}^3\) |
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1. \(25^\circ\text C,~75^\circ\text C\)
2. \(40^\circ\text C,~60^\circ\text C\)
3. \(20^\circ\text C,~80^\circ\text C\)
4. \(30^\circ\text C,~70^\circ\text C\)
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| 1. | \(L(1+\gamma\theta)\) | 2. | \(L\left(1+\dfrac\gamma2\theta\right)\) |
| 3. | \(L\left(1+\dfrac\gamma3\theta\right)\) | 4. | \(L\left(1+\dfrac{2\gamma}3\theta\right)\) |
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