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Calculate the amount of heat radiated pe...

Calculate the amount of heat radiated per second by a body of surface area `12cm^(2)` kept in thermal equilibrium in a room at temperature `20^(@)C` The emissivity of the surface `=0.80` and `sigma=6.0xx10^(-s)Wm^(-2)K^(-4)` .

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The correct Answer is:
B, D
`A=12 cm^(2)=12xx10^(-4)m^(2),`
`T=20^(@)C=293^(@)K,`
`sigma=6xx10^(-8)W//m^(2)-K^(4)`
`Q=AeST^4` ltbrge12xx10^(-4)xx0.8xx6xx10^(-8)xx(293)^4`
`=0.4245=0.42`.
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HC VERMA-HEAT TRANSFER-Exercises
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  4. Assume that the total surface area of a human body is 1-6m^(2) and tha...

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  5. Calculate the amount of heat radiated per second by a body of surface ...

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  6. A solid aluminium sphere and a solid copper sphere of twice the radius...

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  7. A 100W bulb has tungsten filament of total length 1.0m and radius 4xx1...

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  8. A spherical ball of surface area 20cm^(@) absorbs any radiation that f...

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  9. A spherical tungsten pices of radius 1.0cm is suspended in an evacuate...

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  10. A cubical block of mass 1.0kg and edge 5.0cm is heated to 227^(@)C . I...

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  11. A copper sphere is suspended in an evacuated chamber maintained at 300...

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  12. A spherical ball A of surface area 20cm^(2) is kept at the centre of a...

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  13. A cylinderical rod of length 50cm and cross sectional area 1cm^(2) is ...

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  14. One end of a rod length 20cm is inserted in a furnace at 800K. The sid...

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  15. A calorimeter of negligible heat capacity contains 100cc of water at 4...

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  16. A body cools down from 50^(@)C to 45^(@)C in 5 minutes and to 40^(@)C ...

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  17. A calorimeter containes 50g of water at 50^(@)C . The temperature fall...

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  18. A metal ball of mass 1kg is heated by means of a 20W heater in a room ...

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  19. A metal block of heat capacity 90J//.^(@)C placed in a room at 25^(@)C...

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  20. A hot body placed in a surrounding of temperature theta(0) obeys Newto...

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