Q. The value of radiation coefficient or the Stefan-Boltzmann constant is

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Q. What is the wavelength band for Ultraviolet rays?

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Q. A black body of total area 0.045 m² is completely enclosed in a space bounded by 5 cm thick walls. The walls have a surface area 0.5 m² and thermal conductivity 1.07 W/ m K. If the inner surface of the enveloping wall is to be maintained at 215 degree Celsius and the outer wall surface at 30 degree Celsius, calculate the temperature of the black body

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Q. What is the wavelength band for solar radiation?

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Q. The relationship (Wavelength)MAX T = constant, between the temperature of a black body and the wavelength at which maximum value of monochromatic emissive power occurs is known as

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Q. A body at 500 K cools by radiating heat to ambient atmosphere maintained at 300 K. When the body has cooled to 400 K, the cooling rate as a percentage of original rate is about

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Q. Two spheres A and B of same material have radius 1 m and 4 m, and temperatures 4000 K and 2000 K respectively. Then the energy radiated by sphere A is

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Q. A small body has a total emissive power of 4.5 kW/m². Determine its surface temperature of maximum emission

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Q. A small black body has a total emissive power of 4.5 k W/m². In which range of the spectrum does this wavelength fall?

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Q. The sun emits maximum radiation of 0.52 micron meter. Assuming the sun to be a black body, Calculate the surface temperature of the sun

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Q. A furnace emits radiation at 2000 K. Treating it as a black body radiation, calculate the wavelength at which emission is maximum

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Q. Four identical pieces of copper painted with different colors of paints were heated to the same temperature and then left in the environment to cool. Which of the following paint will give fast cooling?

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Q. A surface for which emissivity is constant at all temperatures and throughout the entire range of wavelength is called

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Q. If radiant energy EB emitted by the black surface strikes the non-black surface. If non-black surface has absorptivity α, it will absorb how much radiations?

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Q. If two surfaces are at the same temperature, then the conditions correspond to mobile thermal equilibrium for which the resultant interchange of heat is zero are

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Q. The absorptivity of black body equals to

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Q. A diathermanous body

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Q. Choose the false statement

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Q. The emissivity and the absorptivity of a real surface are equal for radiation with identical temperature and wavelength. This law is referred to as

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Q. With an increase in wavelength, the monochromatic emissive power of a black body

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