Q. Energy released by a radiating surface is not continuous but is in the form of successive and separate packets of energy called

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Q. The electromagnetic waves are emitted as a result of

(i) Vibrational movement
(ii) Rotational movement
(iii)Atomic or sub-atomic particles comprising the matter

Identify the correct statement

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Q. Thermal radiations occur in the portion of electromagnetic spectrum between the wavelengths

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Q. A perfectly black body

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Q. What is the wavelength band for cosmic rays?

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Q. For a prescribed wavelength a black body radiates how much energy at the temperature of body?

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Q. “Radiation emitted by a black surface is a function of wavelength and temperature but is independent of direction”. Choose the correct answer

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Q. The distribution of radiant energy is non uniform with respect to

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Q. “Spatial distribution is also known as directional distribution”. Choose the correct option

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Q. Thermal radiation strikes a surface which has a reflectivity of 0.55 and transmissivity of 0.032. A quantity known as flux is found out to be 95 W/m². Determine the rate of incident flux.

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Q. What is the wavelength for visible light?

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Q. Radiant energy with an intensity of 800 W/m² strikes a flat plate normally. The absorptivity is thrice the reflectivity and twice the transmissivity. Determine the rate of absorption

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Q. A thin metal plate of 4 cm diameter is suspended in atmospheric air whose temperature is 290 K. This plate attains a temperature of 295 K when one of its face receives radiant energy from a heat source at the rate of 2 W. If heat transfer coefficient on both surfaces of the plate is stated to be 87.5 W/m² K, workout the reflectivity of the plate

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Q. On clear night there is radiation from earth’s surface to the space. On such a night, the water particles on the plant leaves radiate to the sky whose temperature may be taken as 200 K. The water particles receive heat by convection from the surrounding air, the convection heat transfer coefficient has a value of 30 W/m² K. If the water should not freeze, make calculations for the air temperature

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Q. “Isothermal furnaces, with small apertures, approximate a black body and are frequently used to calibrate heat flux gauges”. Chose the correct answer

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Q. “A surface element emits radiation in all directions, the intensity of radiation is however same in different directions. Choose the correct answer

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Q. The energy emitted by a black surface should not vary in accordance with

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Q. Likewise the amount of emitted radiation is strongly influenced by the wavelength even if temperature of the body is

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Q. A small body has a total emissive power of 4.5 kW/m². Determine the wavelength of emission maximum

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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 emissive ability of the sun’s surface at that temperature

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