Q. The absorptivity of a surface depends upon

(i) Direction of reflected radiation
(ii) Temperature of the surface
(iii) Composition

Identify the correct statements

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Q. What is the absorptivity of gray body?

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Q. A body that reflects all the incident thermal radiations is called a

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Q. Energy strikes a vertical hemispherical plate with an intensity of 640 W/m². The absorptivity is thrice the transmissivity and twice the reflectivity. Determine the rate of absorption

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Q. Let 220 W/m² of radiant energy is absorbed by a convex surface, 90 W/m² is reflected and 40 W/m² is transmitted through it. What is the value of absorptivity?

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Q. For a grey surface

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Q. Which quantity can be neglected for gases?

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Q. Absorptivity of a body is equal to its emissivity

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Q. Electromagnetic waves strikes a hot body maintained at 900 degree Celsius which has a reflectivity of 0.66 and a transmissivity of 0.022. Let the absorbed flux be 60 W/m². Determine the rate of incident flux

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Q. Radiation heat transfer is characterized by

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Q. Which is true regarding radiation?

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Q. Radiation exchange occurs in

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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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