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Perfect black body: select the correct defining property. Among the listed statements, identify the defining characteristic of an ideal black body in radiation heat transfer. Choose the correct option.

Difficulty: Easy

is black in colour
absorbs heat radiations of all wavelengths falling on it
reflects all the heat radiations
transmits the heat radiations

Correct Answer: absorbs heat radiations of all wavelengths falling on it

Explanation:

Definition
An ideal black body has absorptivity = 1 for all wavelengths and directions; it absorbs all incident radiation. Colour in the visible spectrum is irrelevant to the idealized definition.

Final Answer
absorbs heat radiations of all wavelengths falling on it.

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