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Chemical Engineering Basics - Engineering

Q1:

Maximum amount of thermal radiation is emitted at all wavelengths at any specified temperature by a/an __________ body.

A grey

B black

C opaque

D white

ANS:A - grey

Real materials emit energy at a fraction "called the emissivity" of black-body energy levels. By definition, a black body in thermal equilibrium has an emissivity of ε = 1.0.

A source with lower emissivity independent of frequency often is referred to as a grey body. Construction of black bodies with emissivity as close to one.