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Q. No.A wire of length \(10~\text{cm} \) and diameter \(0.5 \text{ mm} \) is used in a bulb. The temperature of the wire is \(1727^{\circ} \text{C}\) and power radiated by the wire \(94.2~\text{W}.\) Its emissivity is \(\dfrac{x}{8}\) then the value of \(x\) is:
(Given \(\sigma=6.0 \times 10^{-8}~ {\text{Wm}}^{-2} {~\text K}^{-4} , \pi=3.14 \) and assume that the emissivity of wire material is same at all)
1. \(5 \)
2. \(4\)
3. \(6\)
4. \(7\)
(Given \(\sigma=6.0 \times 10^{-8}~ {\text{Wm}}^{-2} {~\text K}^{-4} , \pi=3.14 \) and assume that the emissivity of wire material is same at all)
1. \(5 \)
2. \(4\)
3. \(6\)
4. \(7\)
Subtopic: Radiation |
53%
Level 3: 35%-60%
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Two spherical bodies made of the same material have radii of \(0.2~ \text m\) and \(0.8~ \text m,\) and absolute temperatures of \(800 ~ \text K \) and \(400~ \text K\) respectively. Assuming the effect of the surroundings is negligible, if the smaller body radiates energy \(E, \) in a given time, how much energy does the larger body radiate in the same time?
1. \(256 E\)
2. \(16E\)
3. \(64E\)
4. \(E\)
1. \(256 E\)
2. \(16E\)
3. \(64E\)
4. \(E\)
Subtopic: Radiation |
82%
Level 1: 80%+
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Q. No.
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