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Heat Transfer - Engineering

Q1:

As per Kirchoffs law, the ratio of the total radiating power to the absorptivity of a body depends on the

A temperature of the body only.

B wavelength of monochromatic radiation.

C both (a) and (b).

D nature of material of body.

ANS:A - temperature of the body only.

Kirchhoff's law states that for a body in thermal equilibrium, the ratio of its total emissive power (or radiating power) to its absorptivity at a given wavelength and temperature is equal for all bodies at that temperature and wavelength. This ratio depends on both the temperature of the body and the wavelength of the radiation, as described by Planck's law and Wien's displacement law. Therefore, the correct option is: both (a) and (b).